Face-Heel Turn: The Old Gods, the Scourge, and Fel/chaos energy have a way of inducing this in people. The number of heroic characters who've turned is too large to conveniently list, but includes Millhouse Manastorm, Fandral Staghelm, and Archbishop Benedictus.
In 5.4, General Nazgrim and the Klaxxi side with Garrosh during the Siege of Orgrimmar.
On the monsters' side, players who are much higher level than a monster can walk very close to one, right where they can be seen, without getting attacked.
Failure Is the Only Option: Unless they decide on another way to justify battlegrounds and PvP servers, peace negotiations between the Alliance and Horde are doomed to failure.
Failure-to-Save Murder: Two of these are what pushed Fandral Staghelm and Leyara's Face-Heel Turns. Fandral blames the Dragonflights for not helping the Night Elves in the War of the Shifting Sands, where his son died; Leyara blames Malfurion Stormrage for not protecting Ashenvale from the Horde, where her daughter died. In a similar sense, Master Apothecary Faranell of the Forsaken used to be friends with Jaina, but now hates her, blaming her for what her former lover Arthas did.
Suna Silentstrike doesn't go so far as to kill the person she has a grudge against, but she is furious with Ban for advocating caution in trying to rescue her captured husband Lin. When she finds Lin dead, a mixture of grief, paranoia and sha influence causes her to strike out on her own, and end up fighting you to the death.
Fake Difficulty: Back in Vanilla and TBC, it was exceptionally difficult to try get gear for entry level dungeons after new tiers were released, due to the playerbase having a tendency to flat out declare themelves "done" with the old dungeons and from that point on. This lead to the Can't Catch Up phenomenon, where players who still needed gear from these dungeons and quests were stuck waiting for a group to form since the players focusing on all of the new stuff wouldn't lift a finger to help unless it was for the new things. It's quite frustrating on both ends, to have to run a dungeon for the umpteeth time because people still haven't learned how to play, but also frustrating when you want to raid but can't because nobody seems interested in what you need to do. Thankfully, this has been fixed as of Wrath and Cataclysm, with each new tier usually coming alongside new 5-men dungeons and badge/Justice Point gear that give easy access to gear equivalent to that of the previous tier, enabling easy access to the new raids.
Due to guild advancement/achievements now giving guild perks, it will be considerably easier to do this. The more achievements and guild XP for things like old world raids, the better perks you get, like instant mail between guild members, remote access to the guild bank (once per hour), and purchasable rewards like heirloom gear that can be given to your lower-level characters to help them progress more quickly.
The Halls of Reflection was this for some people. (note: for some) It required perfect cooperation with the group to survive the waves. Wiping on a wave before the two bosses (before 5th and 10th) required you to start over from the first and sixth waves, respectively. It was also common for random players to drop group as soon as Halls of Reflection showed up as the random heroic.
Fallen Hero: Arthas, Illidan and Kael'thas are examples.
Death Knights. "A hero, that's what you once were."
The game uses the term "fallen hero" quite a bit, but in many cases that simply refers to the hero dying rather than being turned evil.
False Flag Operation: Liam Greymane and the player pull off one to trick an Ettin into attacking the Forsaken. First the player kills several of his Ogre minions, steals his war banner, and drops it in front of the oncoming Forsaken. Liam then declares his intention of driving the Forsaken out of Gilneas, on this ancient Greymane war banner, causing the Forsaken to spite him by tearing it down, just in time for Koroth the Hillbreaker to show up.
False Innocence Trick: There's a quest in the Arathi Highlands where you're contacted by an earth princess named Myzrael, who seeks your help to escape her confinement. To free her, you kill some of her guardians and release her from her crystal prison, where you find out that she's evil. Sort of subverted though, in that she was driven to madness by the Old Gods, and now resides in Deepholm, where she is once again sane and good.
Fanon Discontinuity: Can happen In-Universe during the Well of Eternity dungeon, where players go back in time to just before the Great Sundering. The official lore has Night Elves killing the Highborne Varo'then before they drive Mannoroth out of Azeroth; but players, disguised as Night Elves, can ignore Varo'then and attack Mannoroth first, causing him to sacrifice Varo'then to restore his health. It is lampshaded with the achievement: "That's not Canon!"
Fan Nickname: Several, such as high-ranking Darnassus druid Fandouche Toolhelm.
Classes that are perceived as requiring no skill to play receive derogatory monikers, such as "Death Knoob" or "Huntard".
Unusually easy fights are often given "loot-" nicknames, implying the designers might as well have placed the loot in a box for players to retrieve. Examples include Loot Reaver and Lootship.
One of the first bits of paid downloadable content is the Celestial Steed, aka Sparklepony.
Fanservice: There seems to be a model to appeal to just about every demographic of the game, including Stripperiffic female models, bare-chested guys, etc. There are also lots of bones thrown to the player base, such as the inclusion of Death Knights as a playable class, Murloc pets gifted to fans who attend Blizzcon, and the like.
Many otherwise poor armor pieces seem to be designed solely for this purpose, to the point where players will intentionally collect them even when they are totally useless from a gameplay perspective. Moreover, the exact same piece of armor that fully covers a male model may inexplicably turn into a Chainmail Bikini when worn by a female.
Amusingly enough, one of the new plate armour models in Cataclysm shows this in reverse, with the male model showing half of the player's chest, and the female model barely showing anything.
Fantastic Drug: According to a lore interview, a Blood death knight's healing blood is addictive to anyone that's healed by it, overusing said blood can cause addictions and eventually withdrawel, making them dependant on the death knight for a fix, sound familiar?
Arcane and especially Fel magic are this, too. One of the best examples is when the high elves' Sunwell was destroyed, cutting them off from Arcane energies and forcing the newly-christened blood elves to suck magic out of living beings to keep from becoming one of the "Wretched".
Fantastic Honorifics: "Magna" is the proper term for a Guardian of Tirisfal, though both of the ones we see (Aegwynn and Medihv) dislike it.
Fantastic Measurement System: As part of the Noodle Cart questline, players have to retrieve 20 "sloshes" of beer from the Alementals in Stormstout Brewery. It is lampshaded by the name of the quest, "Is That A Real Measurement?"
Blue dragons have names ending in "gos" (Kalecgos and Malygs) for males. Female names end in "gosa" (such as Sindragosa or Madrigosa). There are a few outliers as Word of God says this naming convention wasn't decided on until the Burning Crusade expansion.
Black Dragons true names end in "ion" for males (Deathwing's true name was Neltharion, for example). Female dragons end in "a" (Sinestra or Onyxia). In the Warcraft universe, black dragons are historically the most evil race and had the most direct contact with mortals, therefore most black dragons are known by nicknames given by mortals, usually based on color (Firemaw, Flamewing, Blacklash).
Bronze dragons names end in "dormu" if male (Nozdormu, Zaladormu). Female bronze dragons have names ending in "i" (Indormi, Nozari)
Green dragons only seem do have naming conventions for females, whose names end in "a" (Ysera, Nishera). Most of the male green dragons identified have no discernible naming convention.
Red dragons have names ending in "strasz" for the males (Korialstrasz, Nostrastrasz). Female red dragon names end in "za" (Alexstrasza, Rheastrasza).
Fantastic Racism: Tons in this game, of course, both from NPCs and from players to some extent. Slightly disturbingly, this extends to the forums where posters will bash one another based on their avatar's race (among many, many other things) as if it were their real one.
The most extreme example is forsaken and living humans, in both directions.
Fantasy Counterpart Culture: Applies to all of the playable races in different ways, and most races including NPCs at least reflect a certain culture's architecture, regardless of their culture. For instance, Blood Elves have mostly Arabian Nights-style architecture, but their culture isn't similar at all—see the main trope page for specifics.
The culture and architecture of the Tauren looks a great deal like those of the Plains Indians.
Trolls are mostly Caribbean Islanders, or an over-the-top pastiche of them. They practice voodoo, worship animalistic gods called loa, and dance capoeira and to a Shakira tune. Also they speak with variations on a New Orleans or Jamaican accent.
As for the Humans: Stormwind resembles Middle Ages Europe in government and architecture. Gilneas, for the most part, is based on 19th century London, with most peasants sounding like they're choking on a cockney.
Orcs seem vaguely African, considering the Barrens' wildlife and the history of shamanism and being enslaved by humans.
Ethereals are based off of the old Arab Trader stereotype.
Goblins, particularly the Bilgewater ones, are a very, very biting parody of Americans, specifically New York and New Jersey. And they constantly sound like they're trying to hustle you.
Uldum is a blatant ripoff of ancient Egypt; it even has pyramids and a variation on the fertility of the Nile.
Night Elven architecture is based on that of Japan and they were isolated from the rest of the world for centuries.
Pandaria is mostly feudal China with some Japanese culture mixed in for flavour. It used to be more of a Fantasy Kitchen Sink of Asian cultures until the Chinese government complained for various reasons.
Gallywix as well, not in the main game perhaps but but definitely in the short story about him.
Fauxshadow: During the early days of Burning Crusade, it was repeatedly established that Grand Magister Rommath is intensely loyal to Kael'thas, seemingly setting him up to side with the mad prince once his allegiance to the Legion was revealed. He doesn't. He was also set to betray the Horde for Twilights's Hammer, but this was also cut out.
Arator wanders around Honor Hold asking various NPCs about his missing father Turalyon, with the implication that we would eventually aid Arator in his quest to find him. We don't; the plot point was dropped (possibly a casualty of the cut "portal worlds" idea) and Turalyon remains MIA.
Faux To Guide: For the Twilight Skies quest, where Horde players take a Goblin Zeppelin to the Twilight Highlands, Hobart Grapplehammer and Assistant Greely give players an airline safety demonstration before they board; it demonstrates that Goblins have a complete disregard for safety, airborne or otherwise.
Hobart Grapplehammer: Greely, would you like to demonstrate how our parachutes work? Assistant Greely: Oh hells no! Those things are death-traps!
Fertile Blood: As powerful beings have powerful blood, the site where a demigod died has massive thorny vines spanning for miles where his blood was spilled.
Fertile Feet: Lifeblood, an Herbalist spell that provides very light healing and haste, causes flowers to sprout around the caster's feet.
A rare Trading Card can be turned in for an item that gives the bearer a temporary cosmetic buff that causes this exact effect.
Red Dragons have "fertile fire breath" as well. At least at the Wrathgate. It makes sense as the Red Dragonflight represent the Aspect of Life.
Fetch Quest: When you're not killing things, collecting Twenty Bear Asses, or reporting to somebody, you're fetching something for somebody and thinking, "Why don't they do it themselves, the lazy gimps..."
An extreme example involves buying a quest-giver a flagon of mead to get him to give you the next quest in a chain, when said beverage can be purchased inside the building he's standing next to, and costs less than the reward you get from him for obtaining it. You really don't get much lazier than that.
Fighting for a Homeland: The Cataclysm destroyed the Zandalari homeland, which is why they have turned evil. They are willing to help their Mogu allies take over Pandaria in exchange for land, but some doubt whether the Mogu will honor that promise.
Final Exam Boss: Blade Lord Ta'yak in the Heart of Fear is the main teacher of Mantid sword fighting, and he has four instructors who teach his techniques to other Mantid. When raid groups reach him, they must defeat the four instructors first, which gives players a chance to see each of the four abilities (Wind Step, Unseen Strike, Tempest Slash and Overwhelming Assault) before fighting the boss, where they will face all four at once.
For Monks doing the class quests on the Peak of Serenity, Master Hight is the last challenge you'll face; he uses most of the techniques the previous trainers had, so players will need Roll, Spear Hand Strike, Paralysis, and Jade Lightning to beat him.
Find the Cure: In Silithus and Tanaris, players run into pairs of Goblins, one of whom is poisoned by the local bugs, and the other sends you out to collect samples so they can create an antidote. Silithus plays it straight, but Tanaris subverts it as the sick Goblin is suffering from food poisoning, due to her husband's lousy cooking.
Not a cure per se, but in Mt. Hyjal in the Rage of the Firelands patch, players get a daily quest to retrieve medical supplies to treat the near-fatally burned Hamuul Runetotem.
Finish Him!: Players get to do this to Arthas at the conclusion of the Icecrown Citadel raid, as well as Archimonde at the end of the Mount Hyjal raid.
Fish People: Murlocs, Mists of Pandaria introduces the Jinyu, Koi fish people who evolved from murlocs who were exposed to the waters of the vale.
Fission Mailed: The climax of the Lich King encounter. The entire raid falls over dead, seemingly a wipe... just in time for Tirion Fordring and Terenas Menethil to resurrect the raid.
Interestingly enough, in-game statistics will count this as a death against the boss.
Fisticuffs Boss: Ty'thar in the Bralwer's Guild is developing a new fighting style: boxing. When you fight him, it plays out like Punch-Out!!.
Five-Man Band: The Gob Squad, an elite group of five goblins consisting of Patch (The Hero), Grit (The Lancer), Ticker (The Smart Guy), Volt (The Big Guy), and Newt (The Chick). Horde players work with them in Azshara and the Twilight Highlands. In the Secrets of Ragefire scenario, players both factions are disguised as goblins and become The Sixth Ranger to the group (even earning the temporary title "Gob Squad Recruit").
Five Races: Per faction as of Burning Crusade, although it bumped up to six each in Cataclysm.
Mists of Pandaria introduces five new races native to Pandaria itself: Pandaren (mundane/cute), Grummles (stout), Jinyu (fey), Hozen (cute?) and Mogu (Sort of a cross between High Men and Fallen).
Orcs have always been a harsh and warlike race, but with Wrath of the Lich King they seem to return to being nothing more than dumb, bloodthirsty brutes, since many major orcish characters - including the new Warchief since Cataclysm, Garrosh Hellscream, are portrayed this way. However, as of Siege of Orgrimmar, there seem to be a few groups- 1)The dumb, bloodthirsty brutes (Garrosh, Malkorok), 2)those opposing them (Thrall, Eitrigg, Saurfang and others), 3)Those who follow the first group out of a sense of loyalty (General Nazgrim), and 4)Those who oppose them for less than noble reasons (The Burning Blade Warlocks).
Flawed Prototype: The misshapen and vicious Troggs were the Titans' first attempt at creating creatures of living stone, but were presumably warped by Yogg-Saron's Curse of Flesh. The Earthen were more stable, and though the same curse eventually turned them into Dwarves, they skipped the whole "degenerate subterranean savages" phase.
Flesh Golem: Abominations, Scourge, Forsaken and other necromancers' constructs, provide us the trope picture.
Follow the Chaos: From the Druid-in-Training quest chain in the Western Plaguelands:
Adrine Towhide: Among other things, Zen'Kiki needs to work on his spell accuracy. I could see his wrath spells spiraling out of control even from here! In fact, I used them as a marker to follow your progress through the woods.
Foreboding Fleeing Flock: In Duskwood, after helping Abercrombie with his project, he asks you to bring a note to the mayor of Darkshire, after which someone runs in with news that wolves are running out of the woods, as though fleeing something, the abomination you unwittingly helped create.
Four Is Death: On the Wandering Isle you meet Jojo Ironbrow, who claims to be able to break anything with his head and does so with bamboo, wood, and stone. When he tries to break a jade statue you took from a hozen village he only manages to hurt his head, but the statue makes an effective battering ram later.
Frazetta Man: Troggs are essentially Frazetta Dwarves. They were created when the Earthen were infected with the Curse of Flesh, but instead of becoming Dwarves, they were twisted into a neanderthal appearance with reduced intelligence.
Friendly Enemy: Although they're on opposing sides, the Night Elves and Tauren have a healthy respect for each other, mainly due to their similar backgrounds and traditions.
Friendly Fireproof: In full effect, but taken Up to Eleven with some Holy spells like the Priest's Penance or Holy Nova, or the Paladin's Holy Shock; they deal damage to enemies, but become healing spells when used on friendly characters.
A similar version applies with some bosses, who can create area of effect fields that provide benefits to them, but harm the players who enter them.
From Bad to Worse: Mists of Pandaria's 5.1 patch. Garrosh orders the theft of a magical bell capable of causing pure chaos whenever it rings. This prompts Jaina to order the expulsion or complete extermination of every Blood Elf man, woman and child in Dalaran. Anduin attempts to get the bell back from Garrosh, but is severely wounded, and only barely survives. Garrosh poisons Voljin and send an army of Kor'kron to enforce martial law on the Echo Isles. Finally, Garrosh has begun to order the capture of various Mogu and Sha for "research", which has bad news written all over it.
From Nobody to Nightmare: Kel'Thuzad's attempts at animating the dead bore little fruit until he traveled to Naxxramas in Northrend and saw the Lich King. Similarly, the Cult of the Damned is largely composed of people who were failures and social misfits, but who now are threats to the living of Azeroth.
R.O.I.D.S - Robust Operational Imbue Derived From Snickerfang
E.P.E.E.N. - Equipment Potency EquivalencE Number (from the April Fools' Day 2010 announcement, in case you didn't figure it out)
D.E.H.T.A. - Druids for the Ethical and Humane Treatment of Animals. Not to mention their associated achievement, D.E.H.T.A.'s Little P.I.T.A.
Furry Confusion: Becomes a plot point in Booty Bay where a rival pirate wants players to kill Tauren pirate Fleet Master Seahorn; Seahorn invokes this by having players return with the head of a certain farm animal (wearing a pirate hat).
Also affected by the same patch, Blackwing Lair's first boss required one person to constantly mind control a Large Dragonkin who then would have to proceed to destroy dragon eggs. At any given point, if the person loses their control over the dragonkin, the entire room will explode causing a party wipe.
With the release of Cataclysm and the Worgen's instanced areas, extremely savvy players who abuse several glitches can escape the instanced area without ever getting Worgen form. This renders you unable to use any of their racials or the Dungeon Finder system.
Game Face: Worgen most obviously, and also shadow priests, who shift into Shadowform for combat, which increase the damage from their shadow spells, and lowers the damage they take.
It's also notable that, while Death Is Cheap for players, storyline NPC deaths are generally irrevocable, unless they are intended to come back later. This is given a Hand Wave by the original implementation of Spirit Healers, who told player ghosts that "it's not your time yet." The fact that many scripted events lament the death of NPCs who will merely respawn next week with fresh loot only makes this more obvious.
Poison and disease (especially the Plague of Undeath) are treated very seriously in the story, with many quests centered around saving (or failing to save) NPCs who have succumbed, but for players, salvation is a cure spell or a short wait away.
One daily quest chain involves treating Hamuul Runetotem, who has been burned very badly by Leyara of the Druids of the Flame, including reducing his swelling, replacing his bandages and easing his pain. Players can be cured up from near-fatal fire attacks easily, and Fire Mages can survive fatal attacks with Cauterize (although they will die without immediate healing).
Mounts are another frequently cited example, as for gameplay reasons they are unable to assist players in combat and some should, lorewise, be sapient and/or hostile to the players riding them.
Players will forever wonder why can't the faction leaders just go around everywhere and kill most of the problems to their kingdoms you have to deal with. Their effectiveness varies, however; while Jaina has millions of health in Theramore, she can be killed somewhat easily in the Battle for Mount Hyjal raid if the player doesn't do a good job of protecting her, although she's significantly more powerful than the other soldiers.
Magic spells and effects are all consolidated into one of six schools (Arcane, Fire, Frost, Holy, Nature, Shadow) regardless of actual lore-based source. Druids' star-based spells, for example, are classified as "Arcane," (and their damage in this element is increased while Balance Druids are in Lunar Eclipse) despite one of the major tenets of druidism being a rejection of Arcane magic sources. Mages and shaman both cast spells of the Fire and Frost schools, but the mages' spells are variations of Arcane magic, while the shamans' spells draw their power from elemental spirits. Nature damage includes both lightning and most poisons. Etcetera.
The Forsaken player race, while undead, are classified as Humanoids by the game engine due to the balance issues an Undead classification would cause with spell and abilities that have different effects on different target types. The paladin Exorcism spell, for example, which always crits against Undead targets, or mages' Polymorph, which doesn't work on Undead. They and Death Knights can also be healed with holy spells with no apparent ill effects, while healing is said to be painful to undead.
The Forsaken language of Gutterspeak exists entirely so that Horde and Alliance players cannot communicate with each other in-game. In lore, the Forsaken remember their human lives, and can speak Common just fine, although one Forsaken claims to have lost the ability to understand his former family's language after rising from the dead.
More language examples! Numerous scenes and events in-game depend on players and NPCs being able to communicate regardless of race, so NPCs such as raid bosses will speak a language all players can read. This could all be explained by everyone in Azeroth being able to understand Common, but gameplay prohibits this.
During the Alliance version of the Battle for the Undercity, Thrall will yell "The Undercity belongs to the Horde once more! Lok'tar!". Players will hear the sound file for this, but the in-game text dialogue will be rendered in Orcish.
This can also happen with pretty much every boss with voiceacting when they are affected by the Warlock's Curse of Enfeeblement, which causes them to speak Demonic in text.
And with the arrival of Mo P, Pandaren player characters are unable to talk to Pandaren of the opposite faction despite coming from the same fairly small island. You actually get given a faction-specific version of the language after leaving the Wandering Isle.
Monks only use their weapons for one attack (jab, which can be glyphed to make it always be bare-handed), but they still need to have weapons equipped to get the needed stats or they'll hit for piddling amounts of damage
Gambit Roulette: In the original game, Onyxia had an extremely complex scheme going on to manipulate herself into absolute control of the throne of Stormwind. This quest sequence was removed after King Varian Wrynn returned in Wrath of the Lich King and Onyxia's schemes were canonically thwarted.
Gayborhood: Not in the game itself, but the "Proudmoore" server is known for its GLBT population.
Gay Option: During the third part of the The Day That Deathwing Came quest series, you take control of Martek, who includes "hot babes" in his slightly exaggerated telling of the story of the day Deathwing came. As the story starts, there are four of Martek's admirers situated around his motorcycle: a orcish lady, a human lady, a night-elven lady, and a blood-elven gentleman. As the quest goes underway, Martek can only choose one his admirers to bring with him in the motorcycle, and which one he chooses is up to the player. Yes, you can choose the blood-elven gentleman, and whichever admirer you choose, the narration text will later inform you that Martek and his admirer share a "tender moment" in the motorcycle as the quest continues.
Admittedly this may have been intended another way. The point stands, though.
The quest text actually specifically refers to the blood elf, in the aforementioned "tender moment", as strapping.
Could explain why she prefers "Chromie," since it ends in the "mi" sound. It might also be (at least among dragons) an androgynous name such as "Bobby/Bobbi".
Generation Xerox: A justified example with Harpies. The female only Harpies will kidnap men from other races and use them for reproductive purposes. However, in times where their numbers dwindle, they can produce eggs, the offspring of which is an exact copy of its mother.
Fungalmancer Glop, meanwhile, takes this trope to the most absurd extreme imaginable. Every generation of the Glop family line is identical to the one before, having the same name, same appearance, same occupation, and exact same response when attacked. Taking out the latest Fungalmancer Glop is a daily quest, and the trope is taken so far beyond eleven that, gee, it's almost as if you're actually killing the same stone trogg every day, and the idea that it's the son of the previous is just a flimsy conceit to justify making it a daily quest.
General Ripper: Conqueror Krenna in Conquest Hold, forcing her sister to covertly oppose her, then fight alongside you against her and her bodyguards.
And as of Cataclysm, a monkey named Spanks wandering around Nesingwary's expedition site in Stranglethorn Vale.
One quest in Vashj'ir involves taking a crate of crab meat to Adarrah after she is shipwrecked. She promises to vouch for your character, saying "I'll tell anyone who'll listen that in my moment of need you gave me a case of crabs..." The player later has to fetch her some lobster tails, and upon returning them to her she tells you "That's some of the biggest, juiciest tail I've ever seen!"
The Sons of Hodir quest Mounting Hodir's Helm as well as the daily quests Polishing The Helm, Blowing The Horn, and Thrusting The Spear.
During the Harrison Jones questline, you'll find the tip of a jeweled spear and have to find the spear it fits into. The quest for doing so is named Just The Tip.
There's a ship in (well, now at the bottom of) Menethil Harbour called the Maiden's Virtue...
Ghibli Hills: Mulgore, Nagrand, Grizzly Hills, the Emerald Dream, Loch Modan, Azshara, and others.
The Ghost: The families of several leaders. The women in Arthas's family are never shown, although his mother and sister are named. The bext examples would be Queen Azshara (until Cataclysm), and the Dark Riders in Duskwood, who are apparently Worgen.
Giant Space Flea from Nowhere: Some of the earlier bosses had no explanation for how they were connected with the rest of the enemies in the dungeon. In the Dungeon Journal, however, most of the bosses have their backstory or relevance to the plot detailed, and lore information is gradually being rolled out for the older bosses.
GIFT: The game's chat is notorious for the racism, homophobia, and lewdness from childish players (who are not all children by the way). Particularly in the Barrens and City Trade channels. The latter connects between all of a faction's capital cities, Shattrath City and Dalaran, meaning that all players looking for raids, trying to recruit for them, or buying or selling goods have to put up with it.
Technically the City Trade channel connects ALL capital cities. If you're a Hordie on a raid in Stormwind, you will still see the Trade Chat of all the Horde cities.
Giving Radio to the Romans: The Warlords of Draenor expansion is based on Garrosh Hellscream going back in time to his homeworld to prevent the orcish clans from drinking the blood of Mannoroth. Instead, he gives the technologically primitive orcs knowledge of modern Azerothian technology, turning them into the Iron Horde.
Global Currency: Generic gold, although there are a few exceptions where a faction has its own special currency, often combined with money, and they still buy your things for normal money as well.
The Burning Crusade and Wrath of the Lich King expansions went crazy adding alternate currency, such as Badges of Justice, Emblems of Heroism, Arena Points, Stone Keeper's Shards, Marks of Honor, and even Dalaran Cooking Awards, none of which were interchangeable and which required the developers to create a special character sheet tab just to manage.
Cataclysm, in its turn, tones down the explosion of emblems such that all PvE and PvP tokens are combined into two tiers of currency apiece, with the "higher" tiers being folded into the lower ones with each new content release, and with everyone's "higher" currency being converted into the "lower" currency to put everyone on equal footing in buying the new gear. The other forms of special currency remain, however.
Glowing Eyes of Doom: It's not Warcraft unless you have glowing eyes! Forsaken, Night, Blood, and High Elves, Draenei, and all Death Knights have them, and some helmets give your eyes this effect while worn. Mounts have them, too.
God Guise: Blizzard has been heavily implying the Night Elf Moon Goddess Elune may be a Naaru in their interviews, though the way they imply it also implies it will stay ambiguous to not anger the players who would not like such a "revelation".
God Mode: A handful of quests in Wrath of the Lich King give the players massive buffs (usually courtesy of a faction leader), making them Nigh Invulnerable and increasing their damage output several times over. Repeated in Cataclysm and taken Up to Eleven in Throne of the Tides: in the final encounter, Neptulon buffs your party's damage at least twenty-fold with PUREWATER — and you need every bit of it to defeat Ozumat.
G-Rated Sex: The spring rabbit pet. When two of them get close to eachother, they'll get HeartSymbols over their heads, they'll hop close to eachother and a bunch of baby bunnies will pop up on the ground in sprays of petals.
Grand Theft Me: One quest has Teron Gorefiend pull this off on the player only to inexplicably release the player after slaying his jailor.
Grave Robbing: The Archaeology profession is all about this, as nothing you find will end up in a museum (except pristine versions of artifacts dug up in Pandaria). Common items are nothing more than Vendor Trash, but with artifacts selling for up to 200 gold per item, it's the most valuable Vendor Trash in the game; while the Rare items are useable by the player and range from trinkets that do weird things, to Infinity Plus One Equipment.
Pandaria also has a variation where you can find an offering of gold at some sort of shrine. Stealing it gives you a one-hour visual debuff calling you out for it and turning your character greyscale.
Gray Rain of Depression: Zhu's Watch is a small town plagued with this, everyone there is very lethargic during a rainstorm. It's no surprise that it's all caused by the Sha of Despair.
The Great Wall: The Serpent's Spine, which was built by the Mogu to keep the Mantid out of their territory.
Grey and Gray Morality: Neither the Alliance nor the Horde is particularly good or evil. Each faction, however, has one race that is considered more peaceful or generally nicer than the others - look for hooves. Both sides have committed a fair share of war crimes though, whether officially sanctioned by racial leaders or done by people acting against orders. By the time you hit level 60 you'll have heard of at least one against your race, and accidentally helped somebody from your side commit another.
Further complicating issues is the outside influence the enemies (both hidden and obvious) have - there is no shortage of hostile factions and traitors. A very large amount of the conflict of Wrath of the Lich King came from formerly loyal allies (Arthas, Wrathgate, the Battle for Undercity) although there are many more examples. Curiously, the Horde seems to have a few more instances of being betrayed and manipulated into war with the Alliance, giving them another opportunity to play the victim.
Likewise, even the most generally evil races tend to have at least one friendly exception, if not an entire faction to interact with, like the Klaxxi for the Mantid.
"Groundhog Day" Loop: The Murozond fight in the End Time involves a giant hourglass that acts as a Reset Button, which allows players to keep the fight in a "Groundhog Day" Loop until the hourglass is used up. With each loop, the players are reset back to their state at the beginning of the fight, presumably at full health and most of their cooldowns reset, while Murozond is unaffected, so all damage he takes carries over.
Guide Dang It: Some quests (Mankrik's wife anyone?), although most are not if you actually read the quest. WOW was one of the first games to consciously try to avert this. Previous big-name MMORPGs such as Everquest and Final Fantasy XI gave no hints at all to their quests.
The quest to find Mankrik's wife is retired as of Cataclysm, as Mankrik finally buried his wife. Good thing too, since the area where her body was has been flooded with lava.
Infamous in the Death Knight starting zone. One quest, which has budding Death Knights steal and return their soon-to-be mount, required the explanation of "press one to turn in your horse" so often in beta that it spawned a guild, <Press One For Horse>.
Tends to be somewhat averted over time as Blizzard makes improvements. In the past, only NPCs displayed exclamation/question marks signaling they could start/end a quest; now objects (wanted posters, statues, etc.) that start/end quests display such marks as well. The in-game map now highlights areas where current quest objectives may be located, e.g. where to find particular mobs, quest items, Mankrik's wife, etc. Items that must be gathered/used as part of a quest now sparkle, making them easier to find, and mobs relevant to current quests are marked as such when moused over.
Many of the quests for Blackrock-centered dungeons were this.
However, the epitome of this trope in World of Warcraft is probably the level 40+ Alliance quest hidden in the hills in the much lower level zone Westfall. The dwarf requires a sack each of barley, corn and rye. They're each hidden in seemingly random corners of Azeroth, but you wouldn't know this, as there are no hints whatsoever. Note that Westfall is known for its many farms and there are sacks of corn lying around everywhere, but no, only the one that's found in a desert on another continent will do. The rest of the chain this quest is part of isn't much better.
Then there was another quest in the classic game that required you to go to a blue dragon named Haleh in Winterspring. The only information the quest gave to you was that the person you needed to talk to you was of dragon blood and he or she may be disguised in a humanoid form. That's it. No hints are given to the character's location. The character herself was hiding on top of a mountain in Winterspring that could only be reached by finding a teleporter in a cave filled with hostile elite blue dragons (yes, you had to slaughter Haleh's own kin just to get to her).
Frequently comes up with raid bosses, whose abilities are not always intuitive (for example, you might have to stack in a certain spot to absorb the damage from a given attack, or kill monsters in a certain order), and groups often require members to watch videos or read guides for bosses. The Dungeon Journal, which shows all of the boss's abilities and how they work, mitigates this though.
Speaking of dungeons and raids, even finding your way back to them after you died can be confusing if you haven't actually been there before. Although many entrances have a graveyard less than 50 yards away now, there are a few puzzling ones still such as Blackrock Mountains (where the same central graveyard is where dead players end up coming from 3 different dungeons, including one from Cataclysm, and they are all pretty far away).
Gunship Rescue: When the Lich King corners you at the end of the Hall of Reflection dungeon, your faction's airship swoops in to save the day and buries him in rubble. Not that it's going to kill him, though.
Half-Human Hybrid: Invoked by pirate Tony Two-Tusk as a lame excuse to deny being a (at the time very literal) deadbeat dad. Tony, a Troll, says his ex-wife's sister's baby isn't his, but of Seadog Fajardo, a Human.
Half Truth: One of the reasons that the Mogu were unprepared for the Pandaren uprising was that the Grummles, created by the Mogu to act as spies, were giving them this. They told the Mogu that the Hozen were digging caves, the Jinyu were talking with the rivers, and the Pandaren were dancing, without telling them the Hozen were punching holes in the Mogu's defenses, the Jinyu were divining the Mogu's military strategy, and the Pandaren were developing their martial arts. As a result, the Mogu became complacent.
Hammer Space: Game Hammerspace - while your inventory is limited, there are no weight restrictions. The lining of your armour is never spoiled by carrying an extra dozen mail shirts around, which you can do. Also, twenty harvested herbs take up one inventory space, but so do Twenty Bear Asses.
Hard Mode Perks: Heroic versions of dungeons are harder but give much better loot. For Cataclysm raids, there's often only one achievement for completing the entire raid on normal, but achievements for defeating each boss on Heroic.
Hard Work Hardly Works: Why Gidwin and Tarenar, two childhood friends and paladins who want to join the Argent Crusade, have evolved into Vitriolic Best Buds. Gidwin, a dwarf was jealous that Tarenar, a blood elf was a natural as a paladin, while he had to work hard to keep up.
Have a Nice Death: The majority of raid bosses and many dungeon bosses taunt or boast upon killing a player, and/or wiping the raid. Some are Take Thats at players and/or various memes. A very few are Apologetic Attackers instead, particularly if they've been compelled to fight, and some bosses, like the August Celestials, encourage players to do better.
Headless Horseman: A Headless Horseman appears in a seasonal event (during Halloween). He flies around setting starting towns on fire and can be fought as a boss. According to the background material, he used to be a paladin of the Scarlet Crusade who went insane after his family was killed, died and was raised as an undead by the dreadlord Balnazzar. He also Rhymes on a Dime.
"Prepare yourselves, the bells have tolled. Shelter your weak, your young and your old! Each of you shall pay the final sum! CRY FOR MERCY! THE RECKONING HAS COME!
Heel-Face Revolving Door: Consider the Forsaken Death Knight. You started out as a regular inhabitant of Lordaeron, maybe even fighting the Scourge. You were killed and resurrected to fight for the Scourge. You then joined the Forsaken rebellion fighting against said Scourge. You were killed (again) and resurrected to fight for the Scourge (again). And then you rebelled and joined the Horde after Light's Hope.
Heel Realization: Earthbreaker Haromm and Wavebinder Kardris don't realize their mistake in torturing the elements until after they're slain.
The elements... what have we done... I can hear them no longer...
Hellish Horse: Warlocks and Death Knights get class specific steeds that are horses with red eyes and flaming hooves, and the Forsaken's racial steed is a skeletal horse. There are also several mounts that are rare drops from bosses, including the Headless Horseman and the Lich King, both of which can fly.
Helmets Are Hardly Heroic: While a helmet is a very important part of your gear set (especially late in the game when meta gem slots are introduced, as they only appear on helmets and the benefits offered by meta gems are too great to pass up), actually displaying the helmet is optional and can be toggled on/off from the interface menu. So if your hat looks stupid and you can't find a good one for transmogrification, you can simply choose not to display it. In-universe, many important NPCs (Garrosh Hellscream, Varian Wrynn) never wear helmets, but some don them on certain occasions (Tiron Fordring and Saurfang in Icecrown Citadel, for example).
Help Help Trapped In Title Factory: One of the fortunes you can find in a fortune cookie or a mysterious fortune card reads: "Help! I'm being held prisoner in a fortune cookie bakery!"
Helping Would Be Killstealing: Averted due to the tagging system. Once a player attacks a monster (and does damage), that monster is tagged and only they or their party gain experience points or loot from it. Newbies that don't know about this system will often accuse people of kill stealing until they are told (often harshly) that the game doesn't allow this. An Anti-Frustration Feature introduced in Cataclysm allows quest-related bosses and many rare creatures to offer kill credit to everyone who does damage to them, regardless of whether they are in the same group or even faction.
Herd Hitting Attack: Oh so many of them. Generally any group of more than five mobs at once will require AOE of some sort unless there's some damaging mechanic triggered by their death (for example, the scorpions in the Firelands explode and give a damage-increasing debuff when they die).
Here We Go Again: In Grizzly Hills there is an alliance quest chain where your character eats some Amberseeds from a bucket. After your quest chain for laxatives to get the Amberseeds back, they go right back in the bucket you ate them out of... for the next adventurer...
Tirion Fordring, atop Icecrown Citadel. "Light give me strength to break these bonds," indeed.
In the Ultraxion battle, this is an additional ability players can use to escape the Twilight realm for a few seconds, which is necessary to avoid some of Ultraxion's more powerful abilities (Fading Light, which kills you upon expiration if you're in the twilight realm, and Hour of Twilight, which does extreme damage to those in the Twilight Realm)
Heterosexual Life-Partners: Quite a few: Tirion and Eitrigg, Varian and Bolvar, Thassarian and Koltira, Asric and Jadaar, Anren and Tholo.
He Who Fights Monsters: Sylvanas is headed down this path in Cataclysm. For starters, she hires the Val'kyr to reanimate corpses into new Forsaken, which Garrosh is utterly disgusted by. And during the Worgen starting experience, she uses the New Plague, despite Garrosh explicitly banning its use. She also uses it on Southshore. Doesn't seem too different from the late Lich King, eh? Garrosh even calls her out on this during the Silverpine Forest questline. Her reply is pretty snarky:
Garrosh: Have you given any thought to what this means, Sylvanas? What difference is there between you and the Lich King now?
Sylvanas: Isn't it obvious, Warchief? I serve the Horde.
And then there's the end of the Western Plaguelands questline, where she kidnaps Koltira Deathweaver to punish him for not despising the Alliance enough and not wanting to harm his friend Thassarian (who is leading the Alliance forces in Andorhal). She heavily implies that torture and brainwashing will be involved.
The Royal Apothecary Society already went down this path in the backstory.
Also in the Worgen starting zone is Lord Godfrey; he had been fighting the feral Worgen for so long, that he wants to kill the player once they've succumbed to the curse, and then tries to sell out King Greymane to the Forsaken when it turns out Greymane is a Worgen.
And then during Silverpine Forest, he gets ressurected as a Forsaken, aids Sylvanas in pushing the Worgen from Silverpine... and then kills her, at point-blank range with his gun So by the time you kill him in Shadowfang Keep, he's not only - quite literally - become one of the enemies Gilneas was fighting, but he's become an enemy to THOSE enemies as well.
Sociopathic Hero: Many of the Knights of the Ebon Blade use quite ruthless tactics against the Lich King, many of which involve maximizing the body count against the Scourge and their allies.
Hijacked by Ganon: The Final Boss of Burning Crusade is Illidan, right? Nope, actually it's Kil'jaeden the Deceiver, a fact totally unhinted at by Blizzard prior to the Sunwell content patch (unless you were well-versed in the lore and managed to put quite a few subtle clues together).
Hit-and-Run Tactics /Kiting: Several bosses and quests involve mobs that are dangerous/suicidal to engage in melee combat and so must be kited. Some examples:
In Molten Core, a hunter may obtain a quest to construct an epic bow. Completion of the quest requires the hunter to defeat 4 individual demons. Two of the demons are deadly in melee range, but can be successfully defeated through kiting.
During the second phase of the Lady Vashj fight in Serpentshrine Caverns, Vashj summons various adds, including a large strider (a biological Tripod Terror) that cannot be tanked in melee range, but must instead be kited by a ranged DPS.
In addition, many ranged classes use kiting as part of their standard PvP tactic, and many melee classes have ways around it.
A lot of rare and elite creatures in Pandaria have abilities that force such tactics to avoid death. The area affected is always clearly visible.
Hitler's Time Travel Exemption Act: Used in several dungeons within the Caverns of Time, in which you travel back to prevent the Infinite Dragonflight from interfering with some apparently disastrous events in Azeroth's history — Arthas' Start of Darkness in "The Culling of Stratholme" and Medivh's "Opening of the Dark Portal" under Sargeras' dominion. The reason you need to do this is that if you don't stop them, the resulting futures would have been much, much worse, thanks in no small part to Nice Job Fixing It, Villain.
Player examples, in the heroic version of throne of the tides, it's very possible for a shadow priest to kill themselves with their own Shadow Word: Death's backlash while they're super buffed and burning down Ozumat. Warlocks also used to have hellfire, which does a good amount of Area of Effect damage at the cost of damaging the warlock, if they were low enough, the damage would kill the warlock (This had strategic importance as dying to hellfire didn't cost repairs, allowing you suicide on a Total Party Kill and avoid gear damage), a patch changed it so that the spell didn't kill you if you hit 1 HP, to a predictable response.
Several bosses have mechanics that work against other mechanics. For example, to defeat Deathwing in the Spine of Deathwing battle, you must kill nine Corrupted Blood adds, have a Hideous Amalgamation soak up all the residue, and kill the amalgamation near the armor plate, forcing it open and enabling you to DPS the tendon.
Its possible to get some bosses or their minions killed by their own attacks, and there is usually an achievement for pulling it off.
Holy Ground: Several, Light's Hope Chapel, Stormwind Cathedral, the Temple of the Moon in Darnassus.
Holy Hand Grenade: Priests and paladins have a number of Light-based attack spells. The spells Penance for Discipline priests and Holy Shock for Holy paladins can be used for healing allies or for attacking enemies.
Holy Nova for Priests does both things at once, as do several Monk abilities.
Homage: The Lich King and the Witch King, C'thun, Yogg Saron, and countless others
Homing Projectile: Unless an attack is supposed to be avoided by moving out of the way (don't stand in the fire), then all ranged attacks will home in on their target. Normally this only manifests as an attack making a few curves to adjust for the target moving, but a slow moving attack on a mounted player will follow the player around until he stops and gets hit.
The Creeping Inferno used by the Devout Harbinger in the Molten Front is an explicit Homing Projectile that players are supposed to run away from until it extinguishes itself.
Ranged attacks usually don't inflict any damage if you ride out of range while the attack is in flight, but the actual effect doesn't disappear until it hits the target (in most cases). This can be played with to get a good look at spell effects, particularly with the fastest flying mounts (which are only slightly slower than some attacks).
Some projectiles are slow moving enough that it's possible to guide them so that they hit the player at a more convenient location (Jin'rokh's Focused Lightning), or destroy or evade them long enough (The Lich King's Frozen Orbs).
Honor Before Reason: Pretty much every order of paladins ever conceived. The Knights of the Ebon Blade have no such qualms, though; one quest is called "Honor is For the Weak".
General Nazgrim reveals that he is only following Garrosh out of a sense of honor.
Horned Humanoid: Ogres have rhino-horns, tauren and female draenei have horns of various styles, and almost all demons have them too.
Horny Devils: Played straight with the succubi (and potentially incubi, who may or may not exist). Averted with the other demons, most notably Talgath.
Horse of a Different Color: Every playable race has their own specific mount. With a bit of effort building reputation, players can ride the mounts of other races. There are also quite a few mounts not specific to any one race, such as bears and mammoths.
Hot-Blooded: Any number of NPCs could certainly qualify for this, but Garrosh Hellscream is certainly the most prominent example of it. In no small part, his hot-bloodedness during the events of Wrath of the Lich King is reason for the re-ignition of hostilities between the Horde and the Alliance, or at least kept cooler heads from mitigating them.
The orc race as a whole, really. They have a racial ability named "Blood Fury," and their standard battle cry is "VICTORY OR DEATH!"
HP to One: Any pet battler worth his or her salt is going to have at least one Terrible Turnip. In order to capture a pet the player needs to weaken it before trying to catch it, and the Terrible Turnip has the Weakened Blow attack, which will always leave the opponent with at least 1HP left.
Prince Malchezar of Karazhan has an attack that temporarily inflicts this on a player, and it also negates any healing cast on the target for the duration of the effect.
Huge Rider, Tiny Mount: In a word, yes. For example, the Tauren, massive bovine-people, can ride a creature that is, to all intents and purposes, a chocobo with the serial numbers filed off. The game attempts to scale the poor creature's size upwards, but even so, it's quite clear the hawkstrider should be getting crushed.
This is the reason why initially, Tauren couldn't ride most of the other racial mounts and gnomes were the only race that could ride their own racial mount, the mechanostrider. It was even planned that Tauren wouldn't have mounts at all, instead using a special ability to increase their speed (like the Worgen later on).
Taken Up to Eleven with a specific subzone in the Storm Peaks. After a long quest chain, you get a perpetual disguise in the shape of the aforementioned Ice Vrykul. You can mount any of your normal mounts, but unlike with the tauren they don't scale up. Hence, you can have a giant ice woman crammed into a flying machine built for a gnome.
Similarly, there are very few things funnier to see than a Tauren Death Knight riding a pony (or even a foal) on the quest to get his (appropriately-sized) Deathcharger mount.
Thorim and Veranus, one of the few proto-drakes large enough to carry him on her back.
Human Ladder: In Uldum, Pygmies are trying to steal dates, but they are too short to reach, so they stand on each others' shoulders in a three-pygmy-tall tower to reach. Players can unleash cathartic revenge on the runts by grabbing a hammer and playing Whack-a-Pygmy.
Reaching the highest reputation level with certain factions will occasionally result in some NPCs greeting/complimenting you as you walk past. The most commonly seen example is probably the two Kirin Tor mages standing by the doorway of the Dalaran flight point.
There are several Easter Eggs where NPCs acknowledge particularly important feats if the player character has done them, but have more impersonal dialogue if not. For example, if a player did the quest chain to enter Onyxia's lair way back in classic (an event that has since been removed), a certain lord general greets the player like an old friend when encountered in Northrend. If the player hadn't done that quest, though, they're just greeted like some stranger.
For Warlocks doing the Green Fire questline, they must infiltrate the Black Temple which is currently held by the Ashtongue Deathsworn, which is the same group you assisted in the old Burning Crusade version of Black Temple. Those who reached Exalted with the Ashtongue are allowed to waltz right on in.
Hybrid Monster: Quite a few of them are hybrids of several species, and sometimes between in-universe species.
Hydra Problem: Megaera is a three headed hydra in the Throne of Thunder, when one of her heads is killed, two more grow in it's place. Megaera still takes damage with each head killed, so it's just a matter of killing seven heads and holding out against the assault from all the extra heads.
I Am Very British: Since Cataclysm brought out the Worgen race, you can spend some time in Gilneas. There are two basic accents to be heard - the Aristocrats all use Received Pronunciation and sound like a bunch of snobs, while everybody else talks like they're choking on a cockney. The player is not exempt. Many men and women alike wear rather badly treated bowler hats and top-hats, and so can you, since they're also quest rewards.
Just in case it wasn't obvious enough, their villages and cities are generally a rip of Victorian London in the grip of a werewolf epidemic, the terrain is mostly pine and oak forests and small farms, and the weather fluctuates between rain and heavy rain. Sometimes it stops raining long enough to hail.
I Approved This Message: A commercial announced the addition of Chuck Norris as an apparently very tough character in the game. An announcer says, "There are five million people playing World of Warcraft, only because Chuck Norris allows them to live," and at the end, Chuck says, "I'm Chuck Norris, and I approve this game."
Ice-Cream Koan: Many of the Pandaren jokes are these. Meditate on this.
Idiosyncratic Difficulty Levels: Heroic, a harder version of the 5-man dungeons that scales them up to be challenging to players at the level cap of that particular expansion (or just more challenging) and reward better gear as a result.
Patch 4.3 added "Raid Finder," an easier version of the 25-man Dragon Soul Raid that is split into smaller chunks, and it continues in Mists of Pandaria.
Idle Animation: All the player races feature animations if you stop moving/doing anything for a few seconds, the example in the aforementioned trope lists a few of these.
"I Know You're in There Somewhere" Fight: Subverted with the Lich King. In the "Heart of Arthas" questline, he taunts Tirion Fordring with trying to redeem Arthas, and that this makes him weak; however, this quest proved that Arthas threw away the last vestiges of his humanity, and Tirion realizes that redemption is impossible, so killing him is the only option.
Double-subverted if you defeat the Lich King while wielding Shadowmourne. One of the special items that you can acquire from the Lich King is Jaina's Locket, which, according to the flavor text, he always wore close to his heart.
Also subverted with the Alysrazor fight, hitting her in a specific phase gives a buff implying there is still some green dragon in there but nothing comes of it besides a convenient buff. Then again, it was pointed out that she willingly turned traitor back when she was a green dragon, and was turned into a fire hawk after being defeated.
I'll Never Tell You What I'm Telling You: A new quest in the Northern Barrens called By Hook Or Crook has you interrogate a Quilboar (Pig-like men) to learn the name of his leader. If you choose to kick or punch the Quilboar he will eventually exclaim that "Tortusk trained us not to break" he will then Lampshade this by saying he "said too much".
Sylvanas Windrunner: Oh, you're still here? I had kind of hoped you perished. You would make a very attractive corpse. Lor'themar Theron: I will take that as a compliment.
I'm A Humanoiditarian: Most accurately, the Forsaken have "Cannibalize" as a racial ability to regain health from humanoid or undead corpses. In fact, you'll probably never need to use regular food again.
Awilo in Dalaran really loves serving up gnome!
Also many/most/really any Troll tribe except the Darkspears (and Revantusk) practice cannibalism.
One quest in Silverpine now sends you after bear meat, but due to Dying as Yourself we find out those bears were actually worgen druids.
Worgen, being basically werewolves, don't seem to shy away from taking bites out of their opponents, sentient or not (This has no affect on gameplay, unlike forsaken, it's just the set up for some "I like my meat rare/bleeding" jokes several NPCs, and the players, make).
In Uldaman, three Dwarves are in a holdout position against the Troggs, an item that might appear at their camp is a cookbook suggesting they've been eating the Troggs they killed. Uldaman is a Titan installation, and an artifact there reveals that Dwarves and Troggs are decendants of the Earthen.
Jez Goodgrub in Winterspring warns you not to accidentally get too close to his cooking fire by mentioning a previous member of your race who fell in ... and was delicious.
An NPC at the new Darkmoon Isle but not at the Faire itself sells items of food heavily implied to be made from each playable race.
Several dragons are impaled in the scenery of the Blade's Edge Mountains in Outland.
Deathwing himself eventually gets run through the ENTIRE Wyrmrest Temple in an averted Bad Future. And he did that himself.
Some bosses, such as Lord Marrowgar, can impale players, and the rest of the raid must often destroy or remove what is impaling the player. The Impale that the Mutated Corruption in the Madness of Deathwing encounter uses, however, is simply a very powerful attack that a tank typically needs defensive cooldowns to survive.
In the Siege of Orgrimmar trailer, Garrosh boasts that anyone who opposes him will be impaled on the spires of Orgrimmar, and the camera shows several who met that fate.
In the Wind Lord Mel'jarak battle, players can get the ability to throw spears at the boss's minions, which impale them and disable them until it wears off. If you try to crowd control too many at once, though, the boss will release all of them from such effects.
Important Hair Colouring: Jaina's hair is bleached white by the Theramore-destroying Mana Bomb, practically signifying her change into a driven Horde hater.
I Need You Stronger: The basis of the Lich King's plan in Northrend. It works pretty well, too. At least, until Tirion Fordring calls upon the power of Deus ex Machina and destroys Frostmourne.
Inevitable Tournament: The Argent Tournament, and, on a lesser scale, the Ring of Blood in Nagrand, the Amphitheater of Anguish in Zul'Drak, and the Crucible of Carnage in the Twilight Highlands.
The Infiltration: On several quest lines, players have to infiltrate an evil group, posing as a member of said group, and then doing quests for them. In one notable case, the Knights of the Ebon Blade send you to infiltrate the Lich King's operation in Zul'Drak as yourself, as a Scourge infectee. In Cataclysm, you disguise yourself as a Twilight Hammer initiate to save Jarod Shadowsong, and in Mists of Pandaria, you can disguise yourself as a Saurok on the Isle of Thunder, enabling you to walk around saurok territory unmolested.
Infinity Plus One Weapon: All the Legendary weapons are this, for their given expansion/patch - and most of them are fiendishly difficult to acquire, save the rare few which simply drop from a boss. The easiest ones to get that aren't boss drops can require several thousand gold on the Auction House to gain the materials - and they tend to be weapons designed for outdated, level 60 content. The two Legendaries in Wrath of the Lich King could take months of farming raids to get all the needed items to start making them, coupled with sometimes counterintuitive requirements during intensive boss battles to forge them. And they then become outclassed.
Informed Attribute: Tauren are supposed to be nice according to the lore, but aside from some Easily Forgiven to Garrosh for killing their leader (admittedly in a duel to the death that he only won because outside interference poisoned his weapon) and not giving a crap about the ensuing coup they haven't done anything to show any kind of distaste for Garrosh's Horde, which is willing to attack neutral nations, use chemical warfare to kill civilians, or just killing civilians who are fleeing the chemical warfare or the mass Mind Control or allying with the Dragonmaw who still enslave dragons who are sentient or more.
Baine and the vast majority of the Tauren are uncomfortable with Garrosh's recent decisions, but realize that they will likely face his wrath if they openly defect like what happened to the Trolls after Vol'jin almost got killed.
Informed Equipment: The transmogrification feature plays this straight in a good way, by letting you reskin your equipment if you don't like how it looks.
In a similar fashion, you can choose to not render your character's headgear and/or cloak.
Smaller equipment such as rings, trinkets, and amulets are not rendered.
If you play a Druid you will rarely see your equipment at all due to the various shapeshifting forms. Likewise for any Worgen unless you bother changing to your human form (and using your other racials puts you back to Worgen anyway)
Informed Flaw: As part of their way to keep the factions balanced, Blizzard likes to imply that they're Not So Different. The problem is, they do a very poor job of actually showing that they're equally morally ambiguous, and oftentimes just tell us or simply insist that they are. Some of the problem comes from the fact that certain things are shown, but only in quests for the opposite faction (and even some of those things are clearly not treated as canon for the factions that perpetrated them).
Injured Vulnerability: The Execute skill only works against targets with less than 20% health left. Since vanilla, many more classes have gained abilities that only work on low health enemies, to the point that the 20%-0% part of a boss fight is now referred to as the Execute Phase.
Although many bosses also get more powerful at this point, so these skills are needed.
Monks have a unique variation that works on non-player targets if their remaining health is lower than the users. Not very useful against bosses, but against normal enemies it can even be used if they have full health.
Insane Troll Logic: One of the male!pandaren's /silly quotes is a wonderful example of this:
It is said, 'if you can't beat them, join them'. I say 'if you can't beat them, BEAT them'. Because they will be expecting you to join them, and you will have the element of surprise!
Instant Gravestone: In the Chinese version, tombstones appear instead of skeletons when a player character dies.
Instant Roast: "Pilgrim's Bounty", the Thanksgiving event, has turkeys that can be hunted. When killed, they turn into a fully-dressed roast.
One reward for completing the event is a non-combat pet that features the same turkey model. Under ordinary circumstances it's fine, but if it comes within a certain radius of a cooking fire it will leap upon it and instantly turn itself into a roast. Now that's efficiency!
Insurance Fraud: On Kezan, new Goblin players need to escape the island by buying their way onto Gallywix's yacht, so they burn down their own headquarters and collect the insurance money. Since Mt. Kajaro is about to blow Kezan to smithereens, the insurance agent isn't about to argue.
In the Troves of the Thunder King scenario, two kinds are available. There are keys you can buy for three Elder Charms of Good Fortune that enable you to bypass a door without finding the switch, and there are Burial Trove Keys you find throughout the chests in the scenario that enable you to open the locked Burial Troves at the end and get some of the best prizes.
As you get more and more drunk in-game, monsters will show as lower levels, your vision will blur more and more, and you will stumble randomly when you try to walk. There are a handful of monsters in-game who can actually force players to deal with this.
During the Brewfest festival, it can even cause you to see pink Elekks.
In the Madness of Deathwing boss encounter, if he succeeds in casting his instant-kill "Cataclysm" spell, your vision will fade to black after you die. Because, well, he technically just blew up the planet.
Some monsters related to the Sha of Fear give debuffs that do this. "Fear of Death" makes your health bar appear to have exactly 1 health left, "Fear of Abandonment" makes everyone near you disappear including the monster you're fighting, and "Fear of the Dark" makes everything but your interface go black for several seconds while a creepy scream plays.
Interface Spoiler: The Trial of the Crusader raid achievements avert this, as all of them go to fairly great lengths to hide the fact that Anub'arak is the final boss.
Played straight in Shado-Pan Monastery, in which the Dungeon Journal lists Taran Zhu as the final boss, but the Challenge Mode dungeon quest is called "A Worthy Challenge: The Sha of Hatred".
Many other achievements give out clues to things that are probably supposed to be more secret, at least from an ingame standpoint.
Interplay of Sex and Violence: The Worgen besides being the most "savage" race in the Alliance (they're werewolves, after all) are also the most shamelessly sexual.
That's nothing compared to some of the removed female draenei flirts.
Interrogating the Dead: In Mt. Hyjal is a quest to interrogate Inferno Lords to find out what elemental they are trying to summon, by killing one and using a potion to resurrect him as a mind slave.
Interspecies Romance: In the Jade Forest questlines for the Horde (in Mists of Pandaria), a young Hozen named Riko that joins the Horde falls for a female Forsaken NPC. Initially, he gets freaked out when he sees what's underneath her cloth-mask (a prosthetic jaw and mouth) and runs away scared because she's undead. But when she's captured in a Jinyu/Alliance trap, he rushes through the entire trap to rescue her, proclaiming he still likes her, even if she has a dead face.
Kalecgos, a blue dragon, seems to have an interest in human women. The first, Anveena, was not actually human and sacrificed herself to restore the Sunwell. As of Mists of Pandaria, Kalec has paired up with Jaina Proudmoore following Theramore's destruction. She even looks a bit like Anveena.
In the Sholazar Basin, there's a human woman named Tamara Wobblesprocket, who happens to be married to the Gnome flightmaster not even twenty paces from her.
Azuregos, a blue dragon, fell in love with a spirit healer while hiding in the spirit realm from players killing him repeatedly for his drops.
In the Shrine of the Seven Stars, there's Ann and Marsha Stockton, a dwarf and human respectively (though their relationship isn't implicitly mentioned, they obviously share a surname and perform flirt animations to one another).
In the Back: Rogues have this as a central part of their class. It's also advantageous for other melee classes to attack their target from behind or the side, when possible, because enemies can parry frontal attacks and many bosses use attacks like Cleave that can hit several enemies in front of them.
Hunter pets now always prefer to attack enemies from the back for those reasons, unless they are used as tanks.
In the Blood: After her battle against Deathwing, which ends with both combatants severely wounded, Alexstrasza comes to the conclusion that Deathwing's very blood is corrupt, and that it extends through his entire bloodline, i.e. every single black dragon; she orders the entire black dragonflight slain.
Rheastrasza's questline in the Badlands involves purifying a black dragon egg from said corruption. The followup "Fangs of the Father" questline shows the outcome of this.
“They wanted to hold me, to keep watch over me – a prisoner in all but name. But I will NOT be held accountable for the sins of my father. My destiny will be my own.”- Wrathion, the Black Prince
Subverted with the Netherwing dragonflight, which are descended directly from Deathwing; due to his lack of influence, or their exposure to the Twisted Nether, they are not corrupt like the black dragons. While the Netherwings are very hostile to humanoids, this comes from their enslavement by the Dragonmaw Orcs, and can be befriended if you liberate them.
In the Hood: Many important armor sets, including tier sets, have hoods as part of the set. They're very popular among NPCs of the Priest class, and also Dark Rangers, inspired naturally by Sylvanas.
Lo'Gosh, one half of King Varian Wrynn was enslaved by orcs and fought in the Crimson Ring.
The Naga ended up on both sides of this. The Bloodwash Naga enslaved the Rockpool Murlocs and had some of them fight for their amusement. Also, the Riplash Naga and the nearby Tuskarr were defeated by the Kvaldir, and those not sacrificed to Leviroth were forced to fight each other.
Corrupted! Thorim is very much into this in Ulduar, watching an eternal gladiatorial fight between some captured mercenaries and a Jormungar, resurrecting them when they die so they can continue. His fight starts when his sport is interrupted.
Irony: With the introduction of the Dungeon Finder during Wrath, and achievement was added that after helping out with 100 heroic dungeon groups you got a title "...the Patient". However the first people to get these titles were people who tended to run through a dungeon as fast as possible, leaving others behind or yelling at them to keep up.
Is This Thing On?: The Spoils of Pandaria encounter is an automated security system with a Goblin voice recording.
Spoils of Pandaria: Hey, we recording?
I Surrender, Suckers: While investigating the Alliance gunship in Deepholm, players beat Mor'norokk the Hateful into submission; but when you try to talk to him for information, he grabs you and intends to throw you to your death.
A Borean Tundra quest line involving helping out Whitefin Murlocs comes to a close with you putting on a murloc outfit and "surrendering" to another group of murlocs so you can infiltrate their camp and kill their leader (complete with waving a white flag as you go along with the ruse).
Item Crafting: 13 different professions, all but two of which can craft to a certain extent.
It Has Been an Honor: As a shoutout to The Rock, Apothecary Baxter says this line to Apothecary Hummel when he is killed during Love is in the Air.
It's Probably Nothing: When Worgen players start, they get bitten and gain a debuff called "Worgen Bite", with this description:
You were bitten by a worgen. The wound looks minor... maybe it'll go away with time?
To put it mildly, it doesn't. In fact, periodically checking on that debuff reveals it's getting worse....
Jerkass: Countless NPCs, for a variety of reasons, but most particularly Varian Wrynn, Fandral Staghelm, and Garrosh Hellscream. Many of the less important ones apparently do this for little other purpose than to give players an excuse to kill them. Players also get the opportunity to be a Jerkass in-game on several occasions:
The Death Knight starting area has you begin as an murdering psychopath before you undergo a Heel-Face Turn.
The "Mystery of the Infinite" quest line in Dragonblight has you be a jerk to yourself, twice, thanks to the magic of Time Travel and a Stable Time Loop.
The Children's Week holiday includes achievements for, among other things, eating junk food in front of your orphan ("Bad Example") and leaving him/her behind when you teleport home ("Home Alone"). In beta, there was an achievement that required you to kill ten enemy players while they had their orphan out, again aptly titled, "Once an Orphan...".
There's also an achievement for throwing a snowball at Cairne Bloodhoof, possibly the nicest faction leader of all (if you're Alliance you have to throw it at Magni Bronzebeard instead). After the Cataclysm, you now throw snowballs at Cairne's son, Baine and Magni's brother, Muradin.
Haohan Mudclaw looks down on Yoon for being a "citypaw" who's ignorant about farming. His own daughter, Gina, makes a point of spending most of her time at the Halfhill Market, because "He thinks he owns everything... and everyone".
One of the dailies at Halfhill Market involves collecting debts for one of the Tillers. Some of the NPCs won't pay initially, but you can threaten them with violence if you feel like it or pay the bill for them, with only costs one gold (easily made up by the payout you get for completing the quest)
Thanks to the, uh, everything that the Horde and Alliance cause when bringing their war to Pandaria, Taran Zhu is not in a good mood when you first meet him, regularly belittling you and both factions, and basically telling you to buzz off whenever you speak to him. He cheers up a little after you knock some sense into-and the Sha of Hatred out-of him during the Shadow-Pan Monastery instance. He's also significantly nicer to non-outsiders.
Jaw Drop: The Orc and human fighting each other in the Mists of Pandaria cinematic trailer do this after a Pandaren interrupted them and began beating them both up at the same time.
Jerkass Has a Point: Taran Zhu. Yes, he's an asshole, but he is right that the Alliance and Horde did unleash the Sha because of their war, and they are strongarming, manipulating, blackmailing, threatening, and otherwise forcing Panderia's native races to choose a side.
Jerk With A Heartof Gold: Moodle the Gorloc, who is the smartest and (one of) the rudest of the Gorlocs /and/ Wolvar you'll meet throughout Sholozar basin. He pets the dog several times through his lines during a quest to save the Mosswalker Gorlocs.
Jiggle Physics: All the females have plenty of jiggle to an ample bust, but the female Tauren and Trolls have it particuarly bad - their idle animation has them stand there breathing, while their massive boobs bounce up and down like they're busy on a trampoline.
Female Night Elves had their jiggling reduced in a patch during Burning Crusade, prompting a short-lived "They nerfed my boobs!" meme.
This now also applies to the Male Pandaren. Their bellies of course.
Jumping Off the Slippery Slope: This appears to be one of Blizzard's favorite ways of generating villains. Arthas, Illidan, Kael'thas, Sargeras, the Scarlet Crusade, Malygos, and probably a lot more.
In the Mists of Pandaria expansion, Horde Warchief Garrosh Hellscream ends up becoming the Big Bad after jumping off the deep end.
"Just Joking" Justification: During the Mid-summer Fire Festival, players get a quest to bring some incense to a fire elemental; the tiny elemental starts growing huge as it burns the incense, and declares itself a herald of Ragnaros and will kill everyone with fire. When the incense is burned up and the elemental returns to its original fun size, it says it was "merely jesting".
Just Like Robin Hood: Subetai the Swift, one of the Mogu emperors and a boss in Mogu'shan Vaults, is described by Lorewalker Cho in the following manner.
An earlier version of that dialogue said he shared his wealth with his subjects. Perhaps that was deemed to be too kind for a Mogu, and as such was changed.
Jungle Japes: Feralas, Un'Goro Crater, Stranglethorn Vale and Sholazar Basin.
Kansas City Shuffle: In the Badlands, the red dragon Rheastrasza purifies a black dragon egg, hoping to spawn a new breed of good black dragons. She blows her cover when she's talking to you, and now has to smuggle the egg out of the region. After having you kill some of the evil black dragons in the area, ending with the egg's mother, she goes to retrieve it, only to be cornered by Deathwing, who destroys her and the egg. When players go to the cave where she was killed, they find a note saying that she swapped the egg with one of her own, knowing that the only way to save the egg was if the black dragons thought it was destroyed.
Ki Attacks: The monk's abilities are based on the use of Chi. One of them is a Ki blast.
Killed to Uphold the Masquerade: The Westfall quest line starts with the murder of the Furlbrows, who were killed because they were the only ones who even knew Edwin VanCleef had a daughter and could identify her, something Vanessa VanCleef (Hope Saldean) had to keep secret while she reformed the Defias Brotherhood.
The virmen, a vermine rabbit-like race in Mists of Pandaria. They're quite weak individually but rely on sheer force of number.
A penguin named Dippy is one of the level 2 opponents you'll face in Brawlpub. It looks harmless enough, and oddly cute when you knock it off its feet with a direct attack. It's not possible, however, to use the usual stuns and roots on it. And if it gets into melee range and manages to use its Peck ability on you....
Razorgrin works pretty much the same since its a shark on land that can only flop around slowly... but his bite is lethal.
Kill Sat: The Titans left 4 in orbit around Azeroth as defenses after they left. Each is named for one of the 4 Keepers of Ulduar.
La Résistance: Much of the Horde (including the player character) becomes this opposing Garrosh's regime in Mists. By midway through, there's an open civil war.
Large and in Charge: Faction leaders tend to be taller than player models or regular NPCs, even if they aren't actually taller than normal in the lore, to make them stand out.
Same for most bosses. Especially in raid dungeons.
Large Ham: Most bosses love to yell hammy lines at you while they're trying to smash you into a pulp. Some of the most memetic examples are Kael'thas, Malygos, Gothik the Harvester, the Headless Horseman, Lord Jaraxxus, Kologarn, Thorim, Sindragosa, and of course Yogg-Saron, who has possibly the best Evil Laugh ever recorded in a game .
Protection Paladin's Ardent Defender will allow them to survive a hit that would otherwise kill them, and instead heal them for 15% of their health.
Subtlety Rogues' Cheat Death ability will give the player a boost of HP when they are hit by an attack that would otherwise kill them, it comes with a debuff that prevents Cheat Death from happening more than once every 90 seconds, so they don't become immortal.
Fire Mages have the Cauterize ability that will give them back 40% of their health when they die, but adding a DoT that deals 48% damage in 6 seconds. Using Ice Block will protect from the debuff, but both Cauterize and Ice Block have a long cooldown (and the latter is limited in use by a debuff).
Death Knights have the Purgatory talent that will make them invincible on a hit that would otherwise kill them, but put a heal absorbing debuff on them that stacks with the damage they continue to take, if they haven't healed off the debuff entirely by the time it expires, they die.
In the Chimaeron encounter, if you have above 10,000 HP and a fatal attack hits you, you will be reduced to 1 HP, barring a few phases, such as toward the end of the fight, in which this ability is removed. The trick for healers to conserve mana is to keep the players (except for the tank) as close to 10,000 HP as possible without going below it.
The Last of These Is Not Like the Others: The quest leading you to Rhea involves a package containing compressed blasting powder, a tempered mithril bomb casing, and some safety goggles; being Goblins, the safety goggles were the hardest thing to find.
Last-Second Chance: The "Heart of Arthas" quest chain is basically Fordring trying to determine if there's anything redeemable left in the Lich King. To the surprise of few, there isn't. This gives Fordring and the Argent Crusade renewed determination to defeat the Scourge.
Though when you do finally kill him, it turns out there was a tiny remnant of good holding the rest back. Whether this was enough to redeem him is left kind of open, but his final words suggest not.
Arthas: I see only... darkness.
Last Stand: There are several quests with "Last Stand" in the name, but in most of them, players beat the odds. The quest called "Last Stand" in the Worgen starting zone, has players following Darius Crowley and his men in a hold-out position at the Light's Dawn Cathedral, in order to buy King Greymane time to evacuate the rest of Gilneas; it ends with the Worgen overrunning the cathedral, killing or turning everyone inside, and it's where the player's previous infection takes over.
There is also a Warrior ability that goes by this name, adding health to a Warrior who is about to die allowing a last-ditch effort.
Late-Arrival Spoiler: The new loading screen for Northrend shows Bolvar wearing the Lich King's helm of dominion, true you might not know who it is, but it does spell out that there's still a lich king.
This is partially due to the severe case of Anachronic Order that was a by-product of the release of Cataclysm. By this point, Arthas' death is well-known, and the fact that Bolvar is the new Lich King is assumed common knowledge to the playerbase. However, none of this is helped by the fact that Northrend is time-locked into the events of Wrath of the Lich King, where Arthas is still (confusingly to new players) the Lich King.
Several Wrath of the Lich King questlines spoil events from Warcraft III, especially from the human and undead campaigns. If you stand in the Ruins of Lordaeron long enough, you can hear the scene in which Arthas kills his father.
Lava Adds Awesome: Many fire-based spells, such as the Shaman spell "Magma Totem", features spell effects giving the impression of lava. Their icons also depict lava/magma in different forms.
Lava Burst is also one of the most damaging spells in a Shaman's repertoire, particularly an Elemental Shaman, because if the target is under the effect of your Flame Shock it crits every time - with even more damage added given a specific Elemental talent.
Molten Core has Ragnaros the Firelord, who wields Sulfuras, a gargantuan lava warhammer.
Several bosses in the Firelands use lava-related attacks. Lord Rhyolith spawns volcanoes, will drink lava and wipe the raid if he reaches the edge of his platform, and after his armor is destroyed, reveals himself as a Magma Man.
Lawful Stupid: Chances are that you'll feel this way at some point for some of the quests you undertake when following orders.
In the expanded universe, Uther the Lightbringer is willing to sentence Tirion to exile for trying to save Eitrigg from being executed merely for being an orc because he disobeyed orders.
When players defeat Maloriak in Blackwing Descent on Heroic mode, Nefarian (boss of the Blackwing raids and infamous Genre SavvyTroll) congratulates them and temporarily grants a vanity title of the sort rewarded for completing difficult achievements. The title is "<Name>, Slayer of Stupid, Incompetent, and Disappointing Minions."
Leave No Witnesses: During the Goblins' escape from Kezan, they run into an Alliance fleet attacking a Horde ship; when the Alliance sees the unidentified ship, they cite this before firing on it. This event leads some Goblins to joining the Horde.
Let's Fight Like Gentlemen: Some bosses/mobs will treat a fight against you as honorable combat. Jan-xi and Qin-xi of the Will of the Emperor encounter in Mogu'Shan Vaults will even bow politely to you before proceeding to beat up your raid group.
Let's You and Him Fight: Lantresor, a half-orc, half-draenei in Nagrand, arranges a heroic version of this, with your assistance.
Level Grinding: It's actually almost completely averted - it's doing quests and raids that gets you the best experience, you'll always have more than one quest going at a timeand there is no shortage of quests either. On the other hand, it's part of the reason for Twenty Bear Asses.
Level-Locked Loot: The only things that aren't implicitly so are the items you get from quests... which you have to be a certain level before they're available for you to accept anyway.
Ley Line: Ley nodes are shown in the elven territory, and Karazhan is highly spooky because every single ley line passes through it.
Malygos's master plan was to reroute every one of these on the planet to run under his fortress, then channel all their power into space, removing magic from the world and thereby preventing mortals from abusing it. That this would most likely result in an Earth-Shattering Kaboom didn't quite register to him.
Light Is Not Good: The Scarlet Crusade and Blood Elves (before patch 2.4 gave them some redemption, anyway).
Limit Break: Rage acts like this, to an extent - built by dealing and taking damage, and allowing the use of powerful attacks.
Loads And Loads Of Sidequests: Believe it or not, the game does have main questlines in most of, if not all of its areas. They're buried so deep in side quests that they sometimes are impossible to make out. Alhough since "Cataclysm", most zones have been greatly enhanced so that most questlines are directly related to the story at hand.
If you attacked players in neutral towns, the guards would slaughter you both, no matter who started it or if they fought back. Cue rogues and hunters griefing by stabbing or shooting a player, then throwing aggro off of them as the guards slaughter the poor victim.
In Gadgetzan and Duskwood (Mostly Gadgetzan), guards would not climb buildings or jump onto roofs, so players would get on there and snipe at players who cannot fight back, while the Guards either simply stand around or run to a ledge and stand there, unable to jump up. This was fixed in an Obvious Rules Patch where snipers were added. This was called "Rooftop Camping".
Ain't No Rule against naming everyone your arena team similar names with only one letter difference to screw up macros.
Priests (as well as hybrid classes) would carry around two sets of gear, a set that was more appropriate for healing and support and another set that was more appropriate for damage. Cue quick-change mods happening where people would appear to be walking around as a healer suddenly draw an axe or go shadowform and slaughter you. Also cue priests who would look like shadow priests suddenly start spamming heals so they wouldn't Shoot the Medic First. likewise, Ain't No Rule against using Transmogrification for the same thing.
One thing that really annoys people in the dungeon and raid finder (Especially the latter) is that there Ain't No Rule against having friend(s) who already are geared queue with you, roll for the same piece of gear (assuming they can use it), and then give it to you since you actually need it. There is nothing saying you can not do this, but the 20 or so who are not playing with two or more friends will typically shake their fists at you in frustration, since they're always getting outrolled by people who already have gear and there are plenty of people who have not won a single piece of gear since 2011.
Fixed in the Mists of Pandaria pre-expansion patch which made all loot in raid finder Bind On Pickup (and unlike BOP dungeon drops, cannot be given to other members of the groupnote A feature designed in case a dispute arose after a roll was completed and the winner gave the item to someone else within a 2 hour interval), randomly given to the winning players (with no loot rolls at all), and non-tradeable. While not perfect, this thoroughly eliminated any attempts at Ninja Looting in raid finder.
A rare example of this which was actually endorsed by the developers involved a Warlock and Engineering combination. Using a warlock talent that would give a buff if you sacrificed your pet, but before they de-spawn, used an engineering item that would have a rare chance to resurrect a dead target, the pet might come back to life, giving them a buff from sacrificing the pet, but also the buff from having the pet active. People claimed it was an exploit, but when mentioned to the developers, they shocked people by saying it was actually pretty clever, so until the abilities were removed with an update, they encouraged people to do this! (Part of the reason it probably wasn't removed was that it had a very rare chance of actually working.)
Lost Forever: Several one-time-only events offered goodies which are otherwise unobtainable. A particularly rare mount could only be obtained after an event requiring countless man-hours from the entire server, for a period of less than a day. Any future new servers will have this event completed already, as well. Add in holiday rewards, anniversary pets, world events, and advertising promotion rewards...
The Battle For Undercity quest chain, which originally followed the Wrath Gate, had been removed in Cataclysm. Before that, Varimathras - an important demonic NPC who was made a killable villain during said quest chain - was removed to players who had completed the quest chain, preventing access to a a few low-level quests which he gave out. However, a new orc NPC was added in patch 3.3. who handed out the same quests as Varimathras did.
Many breadcrumb quests become unavailable if you go to the quest giver that breadcrumb quest would take you to before taking said quest. Luckily, said quests are typically not required for quest achievements, and usually only give a token amount of experience or gold.
Some achievements are no longer obtainable, whether from being tied to a one-time event (such as logging in during World of Warcraft's anniversary) or from removed content (such as completing the original Zul'Gurub, or maximizing weapon skill), and those that are become Feats of Strength, worth no points.
Many NPCs and quests from the original World of Warcraft were wiped off the map in the Cataclysm expansion or otherwise went missing without explanation. Well, apart from the fact that a psychotic black dragon had recently wreaked major havok across the kingdoms and killed millions throughout the world.
Oddly enough, many NPCs that were made redundant from certain changes still stick around, such as additional profession trainers (there used to be one for each rank) or the class trainers (while they still offer a few services, there is no need for one for each class in every capital city)
Mists of Pandaria introduced the Black Market, an NPC auction house where many (formerly) Lost Forever items such as unique mounts and old raid loot are put up for bidding at exorbitant prices.
Lost in Translation: Many of the game's names, particularly those of orcs, rely on the ability of English (and other Germanic languages) to string nouns together in Luke Nounverber patterns; "Hell-scream," "Blade-fist," etc. This is completely lost when the game is translated into Romance or Slavic languages, which don't have this ability, resulting in awkward names like "Garrosh Grito Infernal."
Luck-Based Mission: Several quests, achievements and boss fights, see the trope page for examples.