Lore of Hearthstone, Episode #15 - One Night in Karazhan

Karazhan

Karazhan

The tower of Karazhan has appeared in Warcraft I, where it was the lair of the human Guardian Medivh. Built by Medivh's mother Aegwynn, his predecessor as the Guardian of Azeroth, Karazhan is a gigantic tower built on a nexus of magical ley-lines in Deadwind Pass. The Guardian is a being with immense magical power that would protect Azeroth from any threats -- including those of the demonic Burning Legion. They were initially members of the Kirin Tor, the council of Dalaran, but Aegwynn saw the politicking among the Dalaran and was disgusted with them. Being the most powerful of any Guardian or any living mage on earth, Aegwynn prolonged her life with arcane magics, and constructed the tower of Karazhan as her own personal base of operations. Aegwynn would give birth to Medivh, who would take over as the new Guardian. Unbeknownst to Aegwynn or anyone else, Medivh carried within him the corruption of the demon lord Sargeras who had battled Aegwynn in ages past, which would influence Medivh to eventually contact the orcs on Draenor, and together create the Dark Portal that would cause the First War between humans and orcs. The maddened Medivh would eventually be put to sword and slain by his friends Lothar, Garona and Khadgar, and he would thank them for freeing him of the madness he's been trapped in. (More on Medivh later on)

In his youth, however, before Sargeras's corruption took root, Medivh did canonically like to throw parties to fool the mages of Dalaran into thinking that he's basically Azeroth's version of a rich brat billionaire. He would invite guests and nobles from all the human kingdoms and create huge lavish parties in order to fool them into thinking that he wasn't even using his magical powers properly. One such party is presumably the basis for the One Night in Karazhan adventure, which took place long before Medivh felt the corruption within himself that would lead to much sorrow. 

Karazhan itself would be opened in World  of Warcraft: The Burnign Crusade as one of the msot iconic WoW dungeons, and a large number (but not all) of these dungeon bosses would be reflected in the Adventure. In Legion, Karazhan would be revamped as a new dungeon ('Return to Karazhan') for higher-level adventurers as Moroes, the old codger, invited demons from the Burning Legion in, but that version of Karazhan isn't particularly reflected here due to being created, y'know, after the Hearthstone expansion is out. So yeah. Disco party!

Bosses & Legendaries:

Being partially based on the Karazhan raid from Burning Crusade, Karazhan the dungeon itself is a very non-linear dungeon, with multiple bosses living in different parts of the tower. I'm only going to talk about the bosses that are relevant to the One Night in Karazhan adventure. Two bosses -- the Magic Mirror and Silverware Golem -- are completely original to Hearthstone, with their equivalents in World of Warcraft's Karazhan being perhaps the ghostly chefs and guests in the Scullery. While some of the bosses in Karazhan are optional and could be fought in different orders, the One Night in Karazhan adventure swaps around a lot of the order of the boss fights regardless.

Note that the 'free Medivh' encounter had Nazra Wildaxe, whose appearance probably is meant to be a callback/foreshadowing to the fact that Medivh opened a portal to Draenor to summon the orcs in the First War. A deleted fight in the 'free Medivh' encounter had you battle the Maiden of Virtue, a Titanic Watcher found in the original Karazhan raid in Burning Crusade, but it was cut out prior to the release of the game.

Prince Malchezaar:

Prince Malchezaar is an Eredar, one of the greatest and highest-ranking demons in the Burning Legion. Malchezaar in Burning Legion has taken control of the tower of Karazhan, and while not much of his motivations has been explained (the events that took place in One Night in Karazhan is, again, original to Hearthstone) he sits atop the highest part of the tower, in a room called Netherspace. Malchezaar is nominally the final boss of the karazhan raid.

Prince Malchezaar fights adventurers by summoning giant infernals into battle, which explains his line "you face not Malchezaar alone, but the legions I command!" (which is a line he also says in WoW). Malchezaar is also noted to be the possessor of several rare weapons, most famous among them Gorehowl, which inexplicably dropped from the Eredar Prince despite it canonically being in the possession of Thrall and later Garrosh Hellscream. Adventurers that raided Karazhan would defeat Malchezaar and send him back into the twisting nether. Beyond that... Malchezaar himself doesn't have that much lore behind him.

Malchezaar would make a cameo appearance as one of the 'memories' summoned by Argent Confessor Paletress in Wrath of the Lich King's Trial of the Champion instance. Warlocks in WoW wearing the set of armour known as the Deathrattle Regalia also have a chance to summon Malchezaar as a temporary ally.

The Chess Event:

Chess Event (TCG)

In WoW, the Chess Event is one of the most unique encounters in the Burning Crusade Karazhan raid. It is the penultimate boss fight before the raid can reach Prince Malchezaar (as opposed to being the first in Hearthstone) where the players take control of the chess pieces and do battle against the Echo of Medivh, who controls the opposing side. Instead of being actual chess pieces that move around, Harry Potter style, the chest event actually features a recreation of the events of Warcraft: Orcs & Humans, using units from the original Warcraft game to represent pieces traditionally seen in a chess game. Also, instead of the black and white side, the battle is between the humans of Stormwind and the Old Horde, and raids would take control of 'their' faction. The King is represented by King Llane or Warchief Blackhand depending on the side, the queen is a Conjurer/Warlock, the bishops are Clerics/Necrolytes, the Knights are Chargers/Wolves (to represent the mounts of the Knights and Raiders in Warcraft I), the Rooks are Water Elementals/Daemons (the most powerful summoned units for each side in Warcraft I) and the pawns are Footmen/Grunts.

Like Hearthstone, the chess pieces in WoW auto-attack and auto-cast spells when moved around. And just like in Hearthstone, the Echo of Medivh will cheat at random intervals in the game, healing his own units, shooting random blasts of fire at your units, or buffing his own pieces. Also note that the Black King and White King artwork from Hearthstone actually depicts Medivh himself, albeit with a crown.

Barnes & the Opera Event:

The Opera Event, expanded to a whole wing in Hearthstone, is actually a single boss fight in World of Warcraft's Karazhan dungeon. One of three encounters can happen -- "Hood", "Oz" or "Romulo and Julianne", being references to the real-life works of fiction Little Red Riding Hood, Wizard of Oz and Romeo and Juliet respectively. Barnes, the Stage Manager, is the main NPC that starts the event -- although in WoW Barnes is an undead ghost, just like most of the beings in Karazhan.


While in life Barnes is a happy opera manager, in death he continues to faithfully do his duties, albeit with a bit of a twist, since the audience (the raid members) will have to actually fight the actors. The 'Oz' play had adventurers fight Dorothee (a human ghost), Tito (a wolf), Tinhead (a mechanical knight), Strawman (a harvest golem) and Roar (a tigon -- a half-tiger, half-man race) and the Crone (a female troll). In 'Hood', the Big Bad Wolf is a gigantic worgen, and he will periodically transform a member into the little red riding hood. Romulo and Julianne are a pair of ghosts that support each other in combat. Some of these mechanics are somewhat reflected in Hearthstone, although you are allied with Dorothee in the Crone encounter.

In Legion, the ghost of Barnes and the Opera Event return with several new plays -- Wikket (Wicked), Westfall Story (West Side Story, albeit with murlocs) and Beautiful Beast (Beauty and the Beast).

Moroes:

Zombie Moroes!

Moroes is Karazhan's steward in life, featured greatly as the long-suffering old butler that Khadgar interacts with in the Last Guardian novel where much of Medivh and Khadgar's stories are told. He was tasked by her friend Aegwynn to watch over Medivh, and would be Medivh's constant friend and companion through the years. In particular, he would be the one to suggest that Medivh throw parties in order to make the Kirin Tor underestimate Medivh's capabilities as a Guardian, as well as to improve the Guardian's sour moods. During one of these parties, Medivh would open the Dark Portal, and rip out the souls of many guests to do so, as well as defeating Aegwynn and killing the blue dragon Arcanagos (a.k.a Nightbane). Medivh spared only Moroes from this event, and the sight drove Moroes half-mad. Medivh would erase part of Moroes' memory of the event, but he would still never be the same as he was before.

Moroes would meet Khadgar when he came to study under Medivh as an apprentice, and the only one to actually last without leaving in frustration. Moroes was described as a particularly thin man who initially made Khadgar think that Moroes was a mutated animal or a ghost. Moroes was polite but rather strange, wearing blinders to prevent himself from seeing the strange visions in Karazhan. As Khadgar and Garona discovered the truth about Medivh, they implored Moroes to escape. While Moroes helped the two to leave, he stayed behind in Karazhan as he had nowhere else to go. When Khadgar returned with the soldiers of Stormwind, he would find Moroes's body, killed by Medivh.

Moroes (TCG art)

In Burning Crusade, Moroes would be revived as an undead by the magics of Karazhan, and continued to serve his master in death. He would be one of the first bosses encountered in Karazhan, and wields two daggers in battle, residing over the Banquet Hall area, filled with the ghosts of the guests Medivh had killed in the past.

In Warlords of Draenor, Moroes might show up in players' garrisons, noting that he has been killed by adventurers many, many times and has been revived by some unseen force as many times. (It's called respawning, but it also does foreshadow the Return to Karazhan dungeon somewhat) While he desired true death, he knew that was not his fate. Moroes would ask adventurers to find an acidic solution to help clean him up. In Legion, Moroes again serves as the boss for a revamped Banquet Hall, where once again he fights adventurers with the aid of the ghosts of his guests. Some scenes from the Last Guardian novel can also be seen in the Return to Karazhan dungeon. Moroes would kill Apprentice Darius, a Violet Eye mage, and, seeing Legion forces marching towards the tower, would see it as a sign of Medivh's return and allow the demons entry into the tower -- something that causes the creation of the Return to Karazhan dungeon. Players can go through a quest to attempt to free Moroes from his curse, but Moroes would note that while his body is still bound to Karazhan, his spirit is free to do as he wills, and would show up as an ally to the adventurer.

Moroes also shows up in the 2016 Warcraft movie, played by Battlestar Galactica alumnus Callum Keith Rennie.

Nightbane (a.k.a. Arcanagos):

Nightbane (WoW)

Nightbane is a bit of a 'secret' boss in the original Karazhan, a skeletal dragon that is easily far more difficult than the nominal final boss of Karazhan, Prince Malchezaar. The Nightbane in One Night in Karazhan depicts the undead dragon while he was still alive. When Medivh opened the Dark Portal at the beginning of the First War, many creatures that were sensitive to magic in Azeroth felt the ripples of magic emanating from Karazhan. The blue dragonflight, custodians of magic, sent one of their own, the mighty Arcanagos, to investigate. Arcanagos arrived alongside Medivh's mother, Aegwynn, and they were confronted by Medivh, who at this point was puppeteer-ed by Sargeras and unaware of what he was doing. Aegwynn was incapacitated by Sargeras-Medivh, leaving Arcanagos alone to face the maddened Guardian. Even the blue dragon was no match for Medivh's power, who struck Arcanagos down from the skies, burning him from the inside out with fel magic. Only Arcanagos's burning bones remained, and the being left behind was the fel dragon Nightbane.

In Burning Crusade's Karazhan raid, players are able to undergo a quest to seek out Medivh's journals and a mystical urn in order to discover the existence and the way to summon Nightbane. While Nightbane was seemingly slain in Burning Crusade, the Return to Karazhan dungeon in Legion once more included Nightbane as a secret summonable boss that the raid can summon by interacting with 5 soul fragments in the tower within a time limit.

(Why is Nightbane not a card, Blizzard?) The depiction of Nightbane in One Night in Karazhan depicts him in his Arcanagos (i.e. still alive) form.

Terestian Illhoof (and also, Kil'Rek)

Terestian Illhoof is an optional boss in Karazhan, a mighty satyr that is located in the Repository sub-area in Karazhan. Illhoof's chamber is accessed by going through a secret passage behind a bookshelf in the library, and killing the satyr would halt the spawning of demons. Like Nightbane, in Karazhan, Illhoof doesn't actually have anything to do with the menagerie area. In both WoW and Hearthstone, Illhoof is able to summon imps to aid him in combat, among them the mighty imp Kil'rek, who seems to be Illhoof's personal servant.

Illhoof is a satyr, which is a race we haven't actually gotten to talk about before. Introduced in Warcraft III alongside the night elves, the satyrs are demons that were once night elves, but during the War of the Ancients, the Highborne Sorcerer Xavius was transformed into the first Satyr by the demon lord Sargeras. In turn, Xavius would curse many of his followers to become the goat-like demons as well, and the satyrs would become one of the most constant foes to the night elves of Kalimdor. Xavius would break ties with the Burning Legion and serve the Old Gods and the Emerald Nightmare, but the satyrs more or less remain independent, some working with the Burning Legion, some working with Illidan Stormrage and some working with Xavius. One of the biggest battles between night elves and satyr is the War of the Satyr, happening shortly after the War of the Ancients, which would cause some night elven druid to unleash the ill-fated pack form which would lead to the creation of the worgen curse. So fierce were the worgens that the satyrs would be permanently shattered and bereft of any central leadership to the present day.

While Illhoof seems to be summoning Sargeras in his Hearthstone dialogue, no such indication is the case in World of Warcraft.

The Curator:

Curator (WoW)

The Curator is a massive arcane golem that is one of the non-optional bosses in both the Karazhan and Return to Karazhan raids. While the Hearthstone card and boss fight expands on his lore as, well, the curator of the area known as the Menagerie, Medivh's little zoo for arcane creatures (expanded to include beasts and dragons in Hearthstone). In WoW, the Curator is a simple boss with simple attacks that functioned more as a 'gear check' boss. His quote in Hearthstone, "the Menagerie is for guests only", is the quote that he says in his WoW boss fight.

Despite seemingly being destroyed by adventurers during the events of Burning Crusade, the Curator was repaired, presumably by the magics of the tower, to menace a group of Night Watch members from Darkshire in a comic, and later in Legion... although by Legion the Curator's has malfunctioned somewhat terribly, turning him far more powerful and sociopathic than normal. To note that the Curator and Zoobot are the only two arcane guardians/golems in Hearthstone to have the 'mech' tag, whereas others (Arcane Giant and Arcane Golem) does not. Presumably those are just flat-out special? You never can tell with Medivh.

Shade of Aran:

Aran

The Shade of Aran is a boss in Karazhan located in the Guardian's Library. He is the lingering shade of Nielas Aran, Medivh's father. Nielas Aran was once a mage of the Order of Tirisfal and the court wizard of Stormwind. Nielas Aran was a particularly powerful mage, earning him membership into the Tirisgarde -- an organization created to finding and capturing the wayward Guardian Aegwynn. Aegwynn, who had became disillusioned with the Order of Tirisfal and the mages who use their position to gain political power, had refused to relinquish her power, and had became so strong that not even the Tirisgarde, an organization of powerful mages, were able to subdue her. Nielas Aran was different, however. Her hounding of Aegwynn caused Aran to realize that he harboured similar opinions of the Council, and eventually they fell in love. Aran and Aegwynn were both powerful magi even without Aegwynn's Guardian powers, which were then imprinted within Medivh. Aran would raise Medivh after he was born in Stormwind Keep. However, when Medivh matured, he was plagued with dreams due to harbouring an essence of the fallen titan Sargeras. In one such dreams, he sought his father out. Aran touched the young Medivh, but the backlash of energies unleashed was so powerful that Medivh was rapped in a trancelike coma for years, while Aran was killed by the blast. How Aran's ghost ended up appearing in Karazhan is unclear, or if Medivh had anything to do with it. Curiously, despite the Hearthstone battle encounter reusing some of the Shade of Aran's quotes in WoW, the quote that refers to Aran as Medivh's father ("My son is quite powerful but I have powers of my own!") has been changed ("The master is mighty, but I have powers of my own"). Not quite sure why.

His boss-specific card, Flame Wreath, is a reference to a unique spell he casts in his boss fight.

Netherspite:

Netherspite (WoW)

The mighty Netherspite is a nether dragon in the Celestial Watch sub-area of Karazhan, Medivh's personal observatory. While most nether dragons in WoW lore come from Outland -- being black dragon eggs brought to Draenor by Deathwing during the Second War and subsequently corrupted by the energies of the twisting nether when Draenor shattered -- Netherspite seemed to be a unique being, presumably created due to Medivh's own magical experiments with portals. Netherspite's boss fight, which is recreated in Hearthstone to some degree, involves portals that unleash beams that give Netherspite buffs, and adventurers would have to block these beams to avoid Netherspite from being too empowered by them. In addition to portals, Netherspite's boss fight includes banishing enemies temporarily, which is represented with his 'Terrifying Roar' sap-esque spell card in his Hearthstone boss fight.

While no real lore behind Netherspite exists in WoW, Hearthstone's promotional material for Karazhan identifies Netherspite as Medivh's lab assistant. Also, note that the Raid Leader -- a card inspired by a memetic video of a poorly-handled Onyxia raid -- has specific dialogue of shouting about standing in beams, a reference to a different 'bad raid' video featuring Netherspite's boss fight.

Medivh, the Last Guardian:

Medivh was born to Aegwynn, a Guardian of Tirisfal. The title of Guardian was gifted to the most powerful mage in all of the mage city of Dalaran, with all the powers of the mages that comprise council of Kirin Tor granted to the Guardian. Aegwynn, however, was a maverick, and refused to bow to the whims of the Kirin Tor council, disgusted by the political bickering. With her magic, Aegwynn prolonged her life indefinitely, and, seeing that the Kirin Tor could not be trusted, Aegwynn decided to not relinquish the power of the Guardian. She lived far longer than any human did, and would give birth to her son, Medivh. Medivh's father was the talented mage Nielas Aran, who once pursued Aegwynn under the orders of the Kirin Tor. Eight centuries before the first war, Aegwynn did battle against a mighty demon -- an avatar of Sargeras. The battle was mighty, but Aegwynn was seemingly victorious. However, unbeknownst to Aegwynn, Sargeras has placed a fragment of his own soul into Aegwynn's body, a fragment which would enter that of the infant Medivh.

After giving birth to Medivh, he would be given to his father Nielas Aran to care, while Aegwynn locked herself within the great tower of Karazhan. Medivh grew up and was quick friends with the prince of Stormwind, Llane Wrynn, and the future hero of the nation, Anduin Lothar. However, Medivh would fall into a fever on the eve of his fourteenth birthday, and unleash a massive blast of arcane energy that killed his father and left him in a coma. So great was the massive blast of magic that a hundred clerics was summoned to to contain Medivh and Aran's combined powers. Medivh would fall into a coma for nearly ten years, tended in Northshire Abbey. He would awake in time during a time of conflict between Stormwind and the trolls of the Gurubashi Empire. Seemingly in control, his childhood friends Llane and Lothar asked for his aid against the Gurubashi trolls. However, Medivh's power was mightier than anyone anticipated, and single-handedly routed the siege around the capital city of Stormwind. Medivh would then journey to Karazhan and meet his mother, Aegwynn, and learn how to control his powers. Aegwynn would leave Medivh in charge of Karazhan as the new Guardian. Medivh would also befriend Moroes, the caretaker of Karazhan, who suggested Medivh throw parties and galas in order to improve his dark moods. Medivh agreed, and this caused him to develop a facade of a carefree, underestimated youth before other kings and mages.

It was around this point when Medivh started to experience moments of blackouts as the spirit of Sargeras began to manifest and slowly take over. Initially, Sargeras was far more subtle, giving Medivh nightmares and causing him to be troubled and obsessed with stopping the Burning Legion. Sargeras would show Medivh the world of Draenor, where the fel-touched orcs rampaged with no enemy to fight. Medivh would contact the orc warlock Gul'dan, and, giving him promises of artifacts of great power, would work together to create the Dark Portal with the swamps of Black Morass. Thus together, Medivh and Gul'dan would create the Dark Portal together, unleashing the savage orcish Horde upon the world of Azeroth, and beginning the First War, tying together the fates of human and orc forevermore. When the Dark Portal was opened, Aegwynn and her dragon companion, Arcanagos, arrived on Karazhan to confront Medivh in Karazhan. However, at this point Sargeras was part of Medivh's psyche. Medivh killed all the guests in Karazhan, burned Arcanagos inside out, and nearly killed Aegwynn. Moroes, the sole survivor, had his memory wiped by Medivh, although he would not be quite the same.

Throughout this era, the mages of Dalaran would attempt to send young mages to apprentice under Medivh, partly to report back to Dalaran as to the enigmatic Guardian's deeds. No apprentice ended up lasting for more than a matter of days, due to Medivh's rather harsh treatments. One, however, gained interest from Medivh -- Khadgar, who apprenticed under Medivh during the time of the First War. Another guest in Karazhan at this point in time was the half-orc Garona, initially sent by Gul'dan to spy on Medivh, but eventually ended up befriending the mage. Medivh continued to feign allegiance with the forces of the humans of Stormwind, although he did not participate in the war, citing a fear of his immense magic power raging out of control. However, the more sinister circumstances behind Medivh's power was discovered by Khadgar, who realized that Medivh had lied to him and he had known of the orcs and the Dark Portal's existence before they are first seen in Azeroth. Khadgar and Garona would meet up with Medivh's childhood friend, the war hero Anduin Lothar, and as one of the final conflicts of the First War, they would storm the tower of Karazhan and do battle against a crazed Medivh, who was completely consumed by Sargeras's corruption at this point. The battle was fierce, but eventually Lothar was able to slay his former friend. Upon his death, the true persona of Medivh emerged, and thanked Lothar and Khadgar as he died.

Medivh's body was buried, but his spirit lingered. Between the First and Third War, Medivh's spirit gained corporeal form, and while the circumstances behind it was shady, Aegwynn was often credited with this act. Now that the energies of the Guardian and Sargeras were both expelled from him,  Medivh noted that this was the first time in his life that he was truly just Medivh. He would travel Azeroth during the events leading up to Warcraft III, acting as a mysterious prophet with the ability to transform into a raven.

Medivh would first appear to the young warchief of the New Horde, Thrall of the Frostwolf Clan, and would give him a dream and premonition of the Third War, where the Burning Legion would wipe out both Alliance and Horde forces. Thrall, trusting this mysterious Prophet, followed Medivh's instructions to cross the sea to Kalimdor. Medivh also arrived on the court of Lordaeron, warning them of the future conflict, but he was dismissed by King Terenas. His attempts to convince Archmage Antonidas of Dalaran was also reproached, but Antonidas's young apprentice, Jaina Proudmoore, listened. Medivh would appear to her after the culling of Stratholme, convincing Jaina to take as many humans as she could and avoid the destruction of the Eastern Kingdoms. Medivh would then appear to Thrall, Jaina and their allies together in Kalimdor, where the humans and orcs were fighting to meet an 'Oracle', which was also Medivh. Informing them of the true nature of the Burning Legion, Medivh brokered a peace between the Alliance and the Horde. He would also later appear in a dream to the night elf leader, Malfurion Stormrage, who would aid the humans and orcs in a final battle to protect the World Tree from the Burning Legion. After the death of Archimonde, Medivh would look upon the victorious mortals, and note how he will now 'take place among the legends of the past', disappearing and noting that he had found some redemption for his previous sins, and that the mortals of Azeroth can defend it now.

Medivh's whereabouts after the Third War, or indeed if he had passed on from the mortal plane, is unknown. Echoes of the great Guardian linger throughout Azeroth in World of Warcraft. A past version of Medivh could be seen in the Caverns of Time instance, where adventurers would travel back to the time of the First War. A magical Echo of Medivh would serve as an opponent in the Karazhan dungeon's chess event, controlling the opposing side. An 'Image of Medivh' also lingers on the Master's Terrace, where he fought the blue dragon Arcanagos, and the remnants of his massive magical power and the ghosts of the people he slew still haunt Karazhan. In Legion, what appeared to be the spirit of Medivh interacted with Khadgar, but this was revealed to be duplicity by a powerful dreadlord. When Khadgar and other adventurers returned to Karazhan in the Return to Karazhan dungeon, what appeared to be the real Medivh appeared to assist them in undoing the magic of the Burning Legion in the tower. Medivh tells Khadgar that he can't stay to fight the Legion, for his help was needed elsewhere, and names Khadgar Azeroth's new Guardian.
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Residents of Karazhan:

Attumen

Cloaked Huntress: While no mob in Karazhan is called a 'Cloaked Huntress', her armour and her summoning quote ("come, Midnight") implies that she is supposed to be Attumen the Huntsman, one of the first bosses in Karazhan... except Attumen was a dude, and the Cloaked Huntress is a lady. Of course, this could simply mean that the Cloaked Huntress was a predecessor to Attumen as Karazhan's stablemaster. In the Karazhan raid, when the Midnight horse is wounded, Attumen will appear and do battle against adventurers. 

Priest of the Feast: Priest of the Feast is original to Hearthstone, although he is clearly one of the (very much alive!) guests to the party in Karazhan. No depressing soul-siphoning or demonic possession here, after all. Also, the Priest of the Feast is yet another card that makes the funnel cake running gag.

Deadly Fork: All of the living silverware is original to One Night in Karazhan, and no equivalent enemy appears in WoW.

Silverware Golem: Ditto for Silverware Golem, who, despite the awesome concept, doesn't actually exist in WoW. 

Pantry Spider: One encounter not replicated in the One Night in Karazhan adventure is the Servant's Quarters, where one of three powerful beasts -- Hyakiss, Rokad or Shadikith -- would appear as a boss. Hyakiss the Lurker is a giant spider, and is accompanied by several lesser spiders. While the Pantry and Cellar Spiders in Hearthstone doesn't exactly look like Hyakiss (Hyakiss' TCG artwork is actually used for League of Explorers' Tomb Spider), it's likely that they were inspired by her. 

Big Bad Wolf (WoW)

Pompous Thespian: Pompous Thespian is original to Hearthstone, although it's clearly associated with the opera hall in Karazhan. He seems to be re-enacting an iconic scene from Shakespeare's Hamlet, albeit with poor Annoy-o-Tron's head in place of Yorick's skull. His death line, 'et tu', is a reference to another Shakespearean quote from Julius Caesar.

Kindly Grandmother/Big Bad Wolf: Kindly Grandmother/Big Bad Wolf is based on the Big Bad Wolf boss from Burning Crusade's Karazhan, one of the three possible encounters for the Opera Event (see Barnes' entry). In WoW, while disguised as 'the Grandmother', the Big Bad Wolf actually appears in the form of an elderly human woman, before assuming his true form as a giant worgen. Note that the Big Bad Wolf is the only time in Hearthstone that worgens are counted as beasts. In Legion's Return to Karazhan dungeon, the Big Bad Wolf can hilariously be found in backstage alongside many other of the original Opera Hall bosses.

Wicked Witchdoctor: Wicked Witchdoctor depicts the Crone, a boss in the Opera Event fought in both WoW's Karazhan raid as well as the One Night in Karazhan adventure. Her name here, of course, is a reference to the character from Wizard of Oz that the Crone homages, the Wicked Witch of the West. The term 'witch doctor' is a rank often held by trolls, indicating their status as powerful shamans of the tribe.

Swashburglar: I'm genuinely not sure just what Swashburglar is meant to reference. While practically every other card in the adventure seems to represent a sub-location in the Karazhan dungeon, Swashburglar is just... the dude from TGT's Burgle artwork with a pirate hat. 

Zoobot: While no mob in Karazhan is specifically called a 'Zoobot', many other arcane guardians do wander around the Menagerie and the Guardian's Library in Karazhan. Zoobot is unique in that it depicts a smaller, cuter version of the traditional arcane guardian.

Arcane Watchman (WoW)

Arcane Giant: The Arcane Giant, like the Curator, is an arcane guardian. While none are specifically called 'Arcane Giant', many lesser mobs in Karazhan are indeed arcane guardians, among them Arcane Watchman, Arcane Protector and the Curator himself.

Menagerie Magician: Menagerie Magician is original to Hearthstone, because, again, the WoW version of the Menagerie is mostly populated with arcane guardians and undead ghosts.

Menagerie Warden: Menagerie Warden is also original to Hearthstone.

Enchanted Raven: Medivh is very much associated with ravens, with his iconic appearance in a Warcraft III cutscene involving him transforming from a raven into a human within Lordaeron's court room. Ravens are also found circling the tower of Karazhan in WoW, Medivh's staff Atiesh is in the shape of a raven, he's got raven feathers on his cloak... and so on. Note that the Enchanted Raven may actually represent Medivh himself, considering the raven in the artwork has the same necklace that Medivh wears.

Arcane Anomaly (WoW)

Arcane Anomaly: Arcane Anomaly is an arcane elemental mob found in the Menagerie sub-area of Burning Crusade's Karazhan. We talked about arcane elementals (a.k.a. mana-surges) in the Classic set, and once more, they're basically large amounts of mana that have coalesced into a living elemental being. Numerous arcane elementals are found both in the Menagerie and the Library, and the card art for Arcane Anomaly does show the elemental throwing around books.

Babbling Book: Babbling Book is unique to Hearthstone. Presumably it's one of the many, many books in Karazhan's large library. 

Ethereal Peddler: The Ethereal Peddler is unique to Hearthstone, and no mob with her name exists in WoW. However, several ethereal enemies can be found in the Guardian's Library (Ethereal Thief and Ethereal Spellfilcher). Also to note that the Ethereal Peddler is the first depiction of a female Ethereal in any Blizzard material, with her gender being distinct due to her voice and her hourglass-esque body shape.

Book Wyrm: (Ha ha, the pun) Book Wyrm is a original to Hearthstone, and the only dragons to appear in WoW's Karazhan is actually only Netherspite and Nightbane. He could, of course, simply be a guest -- this is pre-creepy Karazhan.

Netherspite Historian: Netherspite Historian is original to Hearthstone, but her name, of course, references the boss Netherspite, perhaps indicating that she is a servant of Netherspite.

Nightbane Templar: Nightbane Templar is original to Hearthstone, although her name refers to the boss Nightbane. Her flavour text also references Nightbane's original name, Arcanagos.

Ivory Knight: Ivory Knight is clearly meant to depict the white knight unit from the Chess Event, or specifically the Hearthstone iteration that uses real giant chess pieces. 

Onyx Bishop: Ditto for the Onyx Bishop, which depicts the black bishop piece in chess.

Malchezaar's Imp: Malchezaar in World of Warcraft doesn't actually have imps or summon imps -- in fact, the only imps found found in WoW's Karazhan are the ones summoned by the satyr Terestian Illhoof, making Malchezaar's Imp more or less original to Hearthstone.

Arcanosmith: Arcanosmith is original to Hearthstone and doesn't have any sort of equivalent in WoW. Likewise for the Animated Shield.

Violet Illusionist: The Violet Illusionist is a member of the Violet Eye, a sect founded by the Kirin Tor of Dalaran to spy on Medivh in Karazhan. Despite Medivh's death in the First War, the Violet Eye remained, and members of the Violet Eye would become quest-givers to adventurers seeking to enter Karazhan in Burning Crusade. No real NPC seems to be equivalent to Violet Illusionist, as far as I can tell.

Runic Egg: No real lore behind Runic Egg, presumably it's just a magical artifact in Karazhan. 

Avian Watcher: Avian Watcher seems to be a minion representation of the glowing-eyed owl fixtures found on Karazhan. Otherwise, not much lore behind it.

Moat Lurker: Moat Lurker is original to Hearthstone, and I'm not 100% sure what it's supposed to be. It seems to be a bog beast, but with a face, I suppose? It certainly doesn't look to be wooden enough to be a botani, which wouldn't be on Azeroth anyway.

Medivh's Valet: Medivh's Valet and his monkey are, obviously, original to Hearthstone.

Abilities & Weapons:

Moonglade Portal, Firelands Portal, Silvermoon Portal, Maelstrom Portal & Ironforge Portal: All five of the 'portal' spells take their inspiration from portals that allow instantaneous travel, found in various capital cities, as well as the portals found in Netherspite's chamber in World of Warcraft (though Netherspite's portals didn't really allow teleportation to other places). Moonglade is a haven for druids and the base headquarters for the Cenarion Circle, a sacred, peaceful location nearby Mt. Hyjal. Firelands is the elemental realm of fire, a parallel dimension to Azeroth where fire elementals live, and home to Ragnaros the Firelord. Silvermoon is the capital city of the Blood Elves. The Maelstrom is the gigantic whirlpool located between the two great continents, and the former site of the original Well of Eternity before it was shattered in the War of the Ancients. Ironforge is the capital city of the dwarves. 

Cat Trick: Cat Trick is original to Hearthstone.

Purify: Purify is an ability for Holy and Discipline Priests added in Mists of Pandaria, which dispels harmful effects on the target such as disease and debuffs.

Kara Kazham!: Kara Kazham is original to Hearthstone, just like all the Beauty and the Beast style living cutlery in the adventure. Quite amusingly, the "Beautiful Beast" Opera encounter in Return to Karazhan would feature an encounter with living cutlery similar to Kara Kazham, despite Legion being created after Hearthstone. Likely to just be a coincidence, though.

Protect the King: Protect the King is original to Hearthstone.

Fool's Bane (WoW)

Spirit Claws: Spirit Claws in WoW is an ability in pet battles used by the pet Xu-Fu, Cub of Xuen. It seems to based on Enhancement Shaman abilities like Rockbiter that added buffs to your weapon to make it stronger, particularly enhancing a 'claw' type weapon.

Fool's Bane: Fool's Bane is an epic one-handed mace that drops from Terestian Illhoof in WoW. Doesn't really have much lore beyond that.