Supposedly in life Sylvanas was very vain. This might explain why she isn't all rotten and gross like most undead: she goes to great length to preserve her body and appearance.
Remember Sean Dempsey from the Cataclysm expansion? You first meet him in the Worgen starting zone, lying on the floor being tended to because he just got mauled by glorified werewolves. And then, you meet him as a corpse strewn across 4-5 different crocolisk stomachs in the Forsaken questline. Then you have him resurrected into a Forsaken, just to have your buddies shoot him in the face. The guy can't catch a break. But how did he end up in those crocolisk stomachs? Again during the Worgen starting zone, you're riding a carriage when you see a broken down one in the road. The Prince at that carriage notes the ogres throwing boulders at your carriages, saying "The one behind us got hit harder, and it tumbled off the road into the swamp." When you go over there, what do you see? Survivors fighting off crocolisks. Chances are, Sean Dempsey was on that carriage, and, wounded and defenseless, was eaten by the crocolisks. If you visit Gilneas later, you'll note the crocolisks aren't there. Chances are, they migrated due to the earthquakes to Southern Silverpine, where you start killing them and discover Sean's mostly digested body parts.
In order to complete quest lines (which is where most of the fun and experience points lies) have to torture prisoners, kill game hunters on a quest for an Animal Wrongs Group (and in a different area you end up killing animals on a quest for those same game hunters, so whatever the morality of the situation, you are doing something wrong), kidnap children, beat up adorable baby monkeys, and just generally do things that doesn't make you feel like you're much of a hero. And then it dawns on you that the Big Bad of the expansion is the Lich King, a paladin who set out to fight evil but who in the course of doing so kept finding himself with the decision of either performing some evil deed or giving up his fight against evil. Each time, he chose to perform the evil deed, and thus he lost his soul one piece at the time and finally turned into an Evil Overlord. And come to think of it, in the trailer for the expansion he threatened you that if you came to Northrend to fight him, the same thing would happen to you. Oh, Crap!...
From the box of the Wrath of the Lich King case: "If you stare long into the abyss... the abyss stares back into you." The other half of that quote is the heart-chilling, "He Who Fights Monsters should see to it that he himself does not become a monster."
It makes even more sense as you find out about Yogg Saron, the Eldritch Abomination whose physical mass is under nearly all of Northrend and whose presence drives people insane.
It becomes even clearer at the end of the fight against the Lich King, as a scripted event kills every player still alive and he boasts how Icecrown, and indeed every event of the expansion, was really just a massive plan to corrupt and ultimately attract the greatest heroes of Azeroth to die at his feet and be raised as his new champions. Unfortunately he hadn't counted on his father's soul returning to resurrect the heroes and hold him helpless as they finish him off.
With Patch 3.2, a few new instance dungeons were added. One of these has a boss that has annoyed players greatly. While he was originally a human Death Knight, in the instance he returns as an Undead Death Knight, with partially decaying skin and everything. When you kill him, he returns as a skeleton, claiming the flesh was only holding him back. And even when you kill his skeletal form, he returns AGAIN as a ghost yelling how he didn't even need his bones to kill you. Then you realize the significance of his name: The Black Knight. And that's (so far) the last time you fight him, too. Before that, you uncovered and fought him on horseback, after which he fled, and then uncovered his scheming AGAIN to lead into the Trial of the Champion boss fight. He just won't stay dead. Nothing compared to Anub'arak, though.. Nothing in the Scourge ever stays dead, really.
The mount the Black Knight rides is a griffin. Much of the forum would like to see it named "The African Swallow". Or European Swallow.
The Headless Horseman:
The Headless Horseman's Mount from the Hallow's End yearly event is an undead horse, which fits with its rider just fine, except the fact that it seemed to be fel-corrupted, with the glowing yellow-green legs/bones. Then you get to Northrend and find out exactly who was pulling the Scarlet Crusade's strings...
In the World of Warcraft manga, the Horseman's backstory is revealed. He used to be a Scarlet Crusader who had a Freak Out after unwittingly killing his family. He went on a rampage before getting decapitated by his comrades, then Balnazzar reanimated him as the Headless Horseman. So yes, this is correct.
How do trolls ride raptor mounts? The raptors clearly wear bridles with bits (the part that goes into the animal's mouth and sits on the interdental region, that space between the teeth and the back of the mouth,) but... how the hell do you get a carnivorous dinosaur to hold a metal bit in his mouth? Provided that they even have an interdental region, what sane person would stick their hands into that mouth? Trolls are the only race that raise and train raptors... And also the only race that can regenerate lost digits and limbs. Coincidence, or Fridge Brilliance?
Blood elf warriors:
Burning Crusade dropped warrior as an available blood elf class for the more popular paladin. Though it was clearly a balance issue, many forumers used the moronic rationale that, "Elves are too delicate to enter heavy melee." Now that blood elf warriors are in Cataclysm, it's Fridge Brilliance. It's a chilling parallel to how World War I destroyed the entire generation of young men for countless villages. There were no blood elf warriors not because elves are somehow ill-suited to fighting, but because so many died fighting Arthas in Warcraft III. Only ten years later (in-game) are level 1 elf warriors finally replacing Silvermoon's best and finest. Instead of a fandumb appeasing move, it becomes something profoundly sad.
Keep in mind that for a Blood Elf to be a warrior, they need, to an extent, to overcome their crippling addiction to arcane magic. A Blood Elf warrior is one of the most noble heroes of their race, and for them to rise up at the time Azeroth needs them most is pure poetry.
Horde players who go through the Stonetalon Mountains do a major quest chain where NPCs will constantly tell you that "Hellscream's eyes are upon you." It seems like just the growing fanaticism of Garrosh's Horde. Throughout the chain you are fighting the Alliance, and you begin to take more and more drastic actions, ending with Overlord Krom'gar attacking a Tauren camp and bombing an undefended druid school to ash. Garrosh portals in, crushes his army, and reminds Krom'gar that mindlessly killing innocents is the Old Horde's way and the New Horde will never forsake honor in battle. he then throws Krom'gar off a cliff and reminds you that his eyes are always on you, so if you cross the line he will find you.
When Wrath of the Lich King came out, several Warlock demons had their abilities changed. The Felhunter (demonic bloodhound) lost his ability to find stealthed (hidden) enemies. This skill was added to the Voidwalker (big purple "darkness elemental" thingy)'s Consume Shadows skill (the skill is channeled for some seconds, during which the Voidwalker regenerates health and, as of the expansion, helps reveal stealthed enemies). If your Voidwalker consumes shadows, of course you can see people trying to hide in the shadows better.
It seems a bit random and Villain Ball-y that, in the Last Rites questline, the Cult of the Damned infiltrator opted to brainwash Thassarian's sister, who had basically no strategic significance. The other victim was a general, all Leryssa seemed to do was piss Thassarian off. But she knew too much. If she kept poking through the records and telling everyone who would listen about her brother, it would come out (as it did, when the player investigated) that he'd been sent on a suicide mission to get him out of the way. And the cultist, through the puppet general, must have ordered that. Obviously, the Lich King's minions wouldn't want his enemies to have Death Knights.
Saronite, a metal which is known to drive people to madness, is named after Yogg-Saron. Rightfully so, too: it's supposedly his solidified blood. In Dragonblight, you learn that the Tuskarr call it "the black blood of Yogg-Saron".
The end of the final battle with the Lich King in which he declares that he allowed Tirion to lay siege to Icecrown Citadel so that whatever champions Tirion brought with him, the greatest of all of Azeroth's adventurers, the Lich King could kill and raise them as the generals of his army. At first it sounds like just an excuse for the Argent Crusade getting as far into his territory as they did; but then you realize that the Lich King has been operating under a "survival of the fittest" pattern for new recruits ever since the beginning; it's how Death Knight initiates determined ranking, and how his Vrykul servants determined who would become elite guard and who would be shamed as zombies. There's also the fact that undead that are too weak to use in combat get fed to Gluth, a fairly difficult raid boss in Naxxramas, and when Tyrannus dismisses Jaina/Sylvanas' men as "not even fit to labor in the quarry" before making them mindless undead. The Lich King does not just amass large armies with his ability to raise the dead, but also is quite discerning about who would be best suited to serve him after being reanimated.
In the Storm Peaks, all of the Keepers of Ulduar were situated in some form of tower, most of them were elevated or up very high, save for Thorim and Freya. Thorim's tower was highest of all, which makes sense, since he is the keeper of thunder, so he can be closer to the clouds and lightning. While Freya's tower was completely on the ground, not elevated at all. Why? She is the keeper of life, and earth, so she can be on the earth so that things can grow.
There was no draenei retcon. The story of the eredar being complicit in the corruption of Sargeras was created and deliberately disseminated by Kil'jaeden. And because he's such an apt...well, deceiver, people in-universe actually thought that it was the truth, and that's why it appears in historical texts (which is how the WCIII game manual should be viewed).
Why does the starting gear for Death Knights sell for a poor amount, even though similar items in the world would vendor for far more? Ignoring the obvious Gameplay and Story Segregation reasons, it's twofold: one, the items are too closely linked to the Lich King that nobody wants them. Secondly, as a Death Knight suddenly freed from the King's control, you actively want to get rid of the things that remind you of who you were. Your own person again, you jump at the chance to get an Outland clownsuit.
The Battle for the Undercity quest, which showed the Alliance and the Horde resuming open war with each other, not only awarded the standard experience, gold and choice of PVE gear, but also offered a PVP trinket. Varian and Thrall realize that now you're going to be fighting the other faction as well as the Lich King.
The ending to Rheastrasza's quest line in the Badlands involved trapping a black dragon and stealing one of her eggs in order to breed a purified black dragon. Through the whole thing, Rhea talked to the player, trying to convince them the the ends justified the means, but her voice comes off like she was trying to convince herself that it was the right thing to do. At the end of the story, she is caught by Deathwing who destroys her and the black dragon egg she stole, but it was a ruse. To get the egg out of the Badlands, she needed to convince the black dragons that it was destroyed, by letting them catch and kill her with a substitute egg, one of her own. All of her previous fidgeting wasn't guilt over what she did to the black dragons, it was anticipation over her impending Heroic Sacrifice.
The Halls of Reflection dungeon in Wrath. Frostmourne still had the souls of everyone it killed in it, and that the souls can come out and harass Arthas (as we see in the battle with him), so that's probably why he keeps it in the Halls of Reflection. The ghosts that you fight are the ghosts of every soldier Arthas killed with the sword, and the reason that he has a room for it is because he's filled with remorse. It's the Halls of Reflection. He leaves the sword in the center and reflects on all the deaths and pain he's caused. So Jaina was right; there is a bit of Arthas left in the Lich King, and he's truly horrified by what he's done. He's still overpowered by the Lich King, but he's still in there. So what used to seem like a fairly random dungeon turned into something really interesting.
Draenei and other races:
In Cataclysm, the draenei didn't receive a new class while every other race did. But it's because they had not fought the Lich King that much. They hadn't done much at all since the Sunwell, only sending a single corp to Valiance Keep and sending representatives to the Argent Tournament. The reason for not getting a new class wasn't because they couldn't think of another one, it was because the draenei weren't shaken by the Cataclysm like the other, native races of Azeroth. It's kind of sad once you think about it. The draenei are almost universally just and fair, but when it comes to world affairs, they are almost completely aloof and separated. They never stop fighting battles of the past, never stop claiming "the Legion's end draws near". The only draenei you see at the forefront of the war against Deathwing are the shamans of the Earthen Ring, far more down to earth and proactive than their paladin and priest brothers and sisters.
In Wolfheart, how aloof the draenei have been becomes pretty clear. The other races were invited to Darnassus to cast their vote on if the worgen should be accepted to the Alliance or not. Tyrande didn't ask the draenei to come because she thought they had all gone back to Outland after the Sunwell. The draenei have done so little that their own allies didn't even know they were still around.
Velen's short story has him encouraging the refugees around the Exodar and Draenei to become more active in the world and do stuff. Sadly nothing has actually come of this for the Draenei.
A bit of Fridge Brilliance: The Burning Legion hasn't been defeated. It's out there, it's still gunning for Azeroth, and this time it's personal. And the draenei are a long lived species, but it's still incredibly likely that fighting or running from the Burning Legion has consumed the better part of most of their lives - so that's the threat they're still focused on.
As of Mists, there are many draenei soldiers in the alliance, the spy group the Alliance enter and quest with in Pandaria (and in the Alliance dailies) has a draenei medic. Velen is more involved with Anduin's training as a champion of light. However, even with this they're among the least represented races in quests and lore compared to the others.
Draenei are having a major role in the upcoming Legion content patch.
Remember the plague that spawned the original Forsaken in the form of mindless zombies? It was spread through contaminated grain, presumably baked into bread and other objects eaten by all of the townspeople, including their children. This means there should be a legion of Forsaken children and teens, yet we see none of them. This implies either the plague didn't work on children, child zombies did exist but don't anymore, or were killed before they were zombies. In the first case, it means infants and children were either killed by their zombie parents or merely starved to death. In the second case, child zombies were probably weaker and more likely to be killed early in the battles. Finally, since the plague took on average three days to kill, it's possible the children died earlier than their parents since diseases tend to hit children more.
Also, Arthas most likely killed children and adults when he charged through those towns.
If there are Forsaken children hidden somewhere, what would their lives be like? All Forsaken can learn and become more powerful, but none change in physical strength or appearance. Even more interesting is what would happen to infant zombies stuck in bodies that physically cannot communicate.
Not to mention that the Forsaken can now create new Forsaken with the Val'kyr's magic. There could be a lot more of these around than we think, specially if Sylvanas is feeling maternal.
Its strongly implied that a new Forsaken is created with surrogate body parts to make up for the ones lost. Naturally, they'd use younger & more healthy organs as surrogates...
Sylvanas' Catalcysm behavior gains a whole new light after reading the short story Edge of Night on the community website. It details how Sylvanas came to make her pact with the Val'kyr, and in which she's shown what the fate of her people would be for want of a Dark Lady. Her animosity towards Garrosh, in particular. Granted, just being Garrosh can give the other Horde leaders reason to dislike him, but Sylvanas' vision showed Garrosh treating her people like disposable reserves and destroying them to the point that they'd throw themselves into bonfires than face the Gilneans. Any hatred Sylvanas has towards Garrosh is brought about by the fact that she knows what he would do if she weren't around.
The three Priest specs each represent a different part of a person. Shadow is the Mind (just take a look at all the abilities, most of them begin with "Mind"), Holy is the Body (it focuses on healing wounds), and Discipline is the Soul (many of its spells are based around the soul; look at talents like "Strength of Soul", "Soul Warding", and the Weakened Soul debuff associated with PW:S). Priests embody mind, body, and soul.
The Broken Base between Alliance and Horde players often complains that the "other side" is getting all the cool toys. For a long time, Horde players complained that the Alliance had most of the territory on Azeroth, and this is later reversed in Cataclysm where the Alliance fan base complains that the Horde is making one-sided gains all throughout the game world. Blizzard is deliberately engendering this embitterment between Alliance and Horde players because that's what the characters (both player and non-player) feel towards each other. Essentially it's Enforced Method Acting applied to a role playing game.
The final battle of the End Time has a mechanic in which you activate an hourglass to, for all intents and purposes, restart the fight. Everything from your position on the battlefield to all of your cooldowns are reset to the state they were in when you first started fighting, with one exception: The boss's health. What makes this Fridge Brilliance is the reason. The boss brags that the hourglass has no effect on him. That's exactly why it works. The hourglass does not effect the boss, so his health stays constant while everyone else is reset.
Why does Tier 9 look so boring and uniform? Because, while the other tier armor sets are relics recovered from dreaded dungeons, this one is a reward for overcoming challenges in the Argent Tournament. We can see in Northrend and the Plaguelands that the warrior and paladin sets (which are recolors of each other) are standard issue Argent Crusade armor.
Darion Mograine could be viewed as an Anti-Arthas character, regarding the relations between each of them and his father. Let's take a look at their biographies:
Starts off as The White Prince, a noble paladin loved by his people and his father is immensely proud of him.
Gradually slips into The Dark Side, performing increasingly selfish acts until he jumps off the slippery slope.
Journeys North to finish his campaign, becoming even more ruthless.
After taking up a cursed blade (and discarding his holy hammer) he turns into an evil death knight.
After being a mind-controlled death knight for a while, in the midst of a losing battle Darion overthrows the Lich King's control by remembering his father. He purifies the cursed sword by giving it to a powerful paladin.
Allied with said paladin, Darion, now with an anti-heroic mindset, ventures North to destroy the Lich King and his undead empire.
Following the Lich King's defeat, Darion is reunited with the ghost of his father. Alexandros thentells Darion that he only retained his sanity because of the faith he had in his son. Darion replies that he would give his life firhim a thousand times. The scene is really touching and is in stark contrast with Arthas' death that occurred just minutes prior.
In 5.3, you get to raid Kor'kron supply lines throughout the Barrens to weaken Orgrimmar and bring supplies to the Darkspear revolutionaries. Think back to Wrath of the Lich King, in a randomly occurring event at Warsong Hold that still happens now, Varok Saurfang tried to tell Garrosh how important and difficult it was to get supply routes, and Garrosh laughed it off, saying that only the warrior spirit of the Horde mattered and they could take what they wanted from the Alliance. Now you get to teach Garrosh just how important supplies are to the war effort.
In the Horde beginning for Mists of Pandaria, Garrosh orders Nazgrim to "paint this new continent red." This can be taken both as paint in the Horde's colors or paint it red with blood. Given Garrosh's later actions, both are appropriate.
Alliance-side, the players' first encounter with Lorewalker Cho can also use the "paint" metaphor. You are asked to cover up a painting by Cho with something of your own work. If you choose to paint "something abstract", the result is red and blue clashing over a field of green. This can easily be interpreted as the player's worry of a major conflict between the Alliance and Horde on Pandaria, and indeed it later happens.
Elementals on Pandaria are completely different from on the rest of Azeroth. While the rest of the planet is known for having elements that are fickle, chaotic and violent, Pandaria's elements are playful, peaceful, and at worst mischievous. Clearly written as a contrast born of the continent's isolation and peaceful inhabitants, it's actually been justified by how magics work in the Warcraft setting. Azeroth's elements are violent because ambient Spirit energy, which helps promote harmony among elementals, is mostly absent on this planet. Shaman manually use that energy to encourage these chaotic elementals to calm down and cooperate. But pandaren developed a whole other application for Spirit—which they call "chi"—to encourage harmony within themselves and in others, and because of the sha threat it became much more widespread among the peoples of Pandaria than any races' Shaman. Pandaren successfully quelled their own elementals as a side effect of their own necessary pursuit of peace.
Two points of Fridge Brilliance regarding the battle with Murozond in the End of Time:
The relative ease of the battle. As we now know, Murozond is the future self of Nozdormu, the Aspect of Time. The other Aspects players have fought against, Malygos and Deathwing, required raids to defeat and yet Murozond is only a five man boss? Putting aside the aid given by the Hourglass of Time, there's actually a very simple reason for needing a less powerful group to fight Murozond: For Nozdormu/Murozond, this battle is taking place after Deathwing's defeat, which means it's taking place after he's lost his full power as an Aspect. He's still powerful, but nowhere near as powerful as he would've been in full Aspect glory like Malygos and Deathwing.
The Hourglass of Time. This was mentioned above but to save some scrolling: As a game mechanic it reverses time to a previous point in the battle, healing the players and resetting their cooldowns. Murozond's health doesn't change, retaining the damage you inflict. As Murozond himself tells you, "the powers of the hourglass do nothing to me!" The Hourglass removes his attacks and danger zones he placed around the battlefield, but does not affect him directly. Murozond seemed to assume the Hourglass was meant as a weapon against him. It was, just not in the way he seemed to think.
In Mount Hyjal you go undercover as a cultist recruit and take up a quest called Mental Training: Speaking the Truth to Power. To accomplish this task you have to answer ten questions that ask stuff like "is the ocean filled with water" and "is ice hot". Now on the surface they are stupidly easy questions that a child could pass. However, one of the biggest risks that the Twilights go through is being exposed to the power of the Old Gods, which can drive them insane. So as a result these questions are used not to test a recruit's knowledge or loyalty, but their reasoning and sanity. Should they fail the tests, then chances are a recruit is driven to the point of insanity that they no longer serve a purpose to the cult.
Why was Vol'jin chosen over all other Horde leaders for the position of Warchief? Vol'jin was the only one who managed to set aside his own pride for the good of the Horde. He asked the Alliance to help take down Garrosh instead of trying to do it alone, and he left the raiders to go flush out Garrosh while he dealt with the chaos in the streets above, instead of acting on his promise to kill Garrosh himself. No other Horder leader, not even Thrall, was able to hold back their pride like that, and that's what makes Vol'jin the best choice for Warchief. Even more fridge brilliance when you consider the event that started the whole siege was the unleashing of the Sha of Pride.
A relatively-minor one reliant on Bilingual Bonus, but the Huojin (Horde) and Tushui (Alliance) Pandaren are not just Red Oni, Blue Oni in leader/tabard color scheme and in philosophy but also in name: "huo" and "shui" in Mandarin are literally "fire" and "water".
It's a subtle one, but when Thrall tells Garrosh he has disappointed him, the tusks of Mannoroth fall off as he awakes/recovers from the fight. Considering how it was his father in the prime timeline that freed the orcs from demon taint, it's a symbolic way of showing that Garrosh really is a disgrace to not only his own father, but the orcish race as a whole because he nearly damned them to a different, but equally as bad evil magic to turn them into bloodthirsty warmongers infused with it to conquer Azaroth.
A key difference between Garrosh and Grommash is that Grom is capable of feeling remorse for his actions, but Garrosh never did. That is why Grom died a redeemed orc and Garrosh didn't. But he will instead go down in history as the orc who nearly doomed the Horde. The opposite of what his father did when he died.
Throughout the last few expansions and expanded universe material, it has been shown that the relationship between the Forsaken and the blood elves has become more strained, despite Sylvanas being the one to bring the blood elves into the Horde. A lot of this is attributed to Sylvanas strongarming Lor'thamar into helping in the Northrend campaign when the blood elves were still recovering from the events of Burning Crusade. There is, however, another likely reason for this. In Warlords of Draenor, blood elf paladins are part of the Horde forces, especially in demon infested areas such as around Shattrath City. Now that they have the Sunwell back, the blood elves (or, at least, their Paladins) are becoming reacquainted with the Holy Light. something which is painful to the undead and the very loss of which is why they call themselves Forsaken to begin with. No wonder they're drifting apart. At best, the blood elves are regaining something the Forsaken can never again have while, at the worst, they're developing a weapon that can be used against the Forsaken should there be any real conflict between them.
In Warlords, the battle of Shattrath ends with Exarch Maraad saving Yrel at the cost of his own life, then Yrel and Durotan teaming up to fend off Blackhand before Khadgar can teleport them out. Every ability used during that cutscene is alsopresent in the game itself. Maraad's barrier on Yrel is the Hand of Protection, Yrel heals Durotan with her Lay on Hands, and Yrel activates Avenging Wrath, which grants a significant damage boost along with the glowing wings, and would also explain how she finally inflicted a serious wound to Blackhand, who'd been No Selling prior to that point.
The legendary quest cutscene in Warlords actually brought a lot of fridge brilliance. Here's a list.
One: Gul'dan binding Grom is a call back to episode 2 of lords of war when he got captured by the orges. Especially with Gul'dan wanting to break Grom's will. The only question that remain to be seen is if Gul'dan will be succesful or not.
Two: Kilrogg doesn't hesitate when he joins Gul'dan and drinks Mannoroth's blood. While it may look like Kilrogg was only fighting for the strongest side, Kilrogg pretty much KNEW what he was getting himself into, since chieftains of his clan can foresee their own death. Kilrogg must have been aware of Garrosh's plan form the very start, and was following his destiny knowing that time traveling messed up the timeline, so if Grom wouldn't carry out destinyhe will.
Thrid and final: With knowledge of the future and the Iron Horde weakened, Gul'dan picked the perfect time to take over the Iron Horde turn it into the true horde, with Kilrogg as his new "Blackhand". In a meta sense, the timeline might be correcting itself.
The Burning Legion sending an invasion force more massive than ever before to Azeroth initially seems to be a reaction to the fact Azeroth's mortal races have fought them off several times before. However, a Wrathguard in the Demon Hunter starting zone claims "Yours is the last world left". It's not just that Azeroth has been so successful, it's that the Legion can now focus all of their forces on Azeroth.
Also involving the Burning Legion, their greatest weapon isn't the massive, nigh-unstoppable army they have. Instead, it's fear and distrust; fear of the use of that army to turn potential threats to their side, and distrust of others who may have already turned and are plotting against you without your knowing. After all, what's better? To waste forces in a fight that you'll win, eventually, or simply "convince" your opponent not to fight and join you? It's exactly the sort of thing Kil'jaeden the Deceiver would come up with.
In the Death Knight order hall campaign, you need to rebuild the Four Horsemen. One of these champions that you recruit that you are very early spoiled on is High Inquisitor Whitemane. Why would this one particularly zealous priest of the Scarlet Crusade be a valid candidate for Death Knighthood? A few things, as it turns out:
From the lines she speaks right as you resurrect her, she quite obviously has visited the same Hell-after-death as Sylvanas did, being audibly relieved that she is no longer dead - a far cry from the "Purge all undeath" stance she took in life. And, like how Sylvanas made a pact with the Val'kyr to keep herself out of that, she is far more comfortable with undeath.
From a line in the quest text to directly recruit her, she claims that the Legion is the source of all of her woes, heavily implying that she knows that the Scarlet Crusade was puppeted by Balnazzar, at least after the fact, and is quite eager to put the rest of the Legion to the sword because of it.
Xavius in the Emerald Nightmare raid is just a reskinned, satyr-like General Vezax and other Faceless One generals. the Old Gods are remaking a Burning Legion creation into one of their own. Of course he'd end up looking like one of their favored monstrosities! They might not be able to transform their minion into a perfect reproduction, given the Legion's own reshaping of Xavius' body, but they can twist and bloat it into the same general shape.
The hidden artifact appearance for the Unholy Death Knight's weapon is the grip and crossguard of the Apocalypse sword with an Abomination's hook replacing the blade and a few minor changes to the accessories on the hilt. The book on your weapons' histories explains that Apocalypse constantly changed hands from Dreadlord to Dreadlord, who infused it with their own knowledge, malice, and disease, sometimes reshaping the weapon before handing it off to the next... and the player has continued that chain by adding in the Scourge's own knowledge, malice, and diseases!
Starting Demon Hunter PC's at level 98, and chronologically during the attack on Black Temple. After taking into consideration the stat squish, PC stats and abilities at level 98 compared to level 70 health pools and damage, and the coefficients on PvP damage and damage reduction...the PC actually would be on rough parity with a level 70 raid boss, especially considering how ridiculously overtuned Burning Crusade raid bosses were. You even get to see how artificially stupid aggro mechanics actually are later, during Illidan's flashbacks.
The Demon Hunters aren't the only class who's Resurrective Immortality gets justified in Legion, Death Knights also get it subtly justified. Icebringer and Soulreaper retain Frostmourne's soul stealing powers, and your character has to enter the blades to gain control. The PC Death Knight has become a Lich. Even more so, unless you use a spirit healer, you need to run back to your body to revive, and that's where your weapons are.
Gul'dan, when aggroed in the Nighthold, will give a small speech about how Varian begged for his life while kneeling before him and how Vol'jin died, screaming in agony as the fel poison ravaged his body. Neither of these things are true... but Gul'dan is so wrapped up in his belief that he's "Darkness Incarnate" that he's deluded himself into believing that the two leaders of the Alliance and Horde were pathetic, crawling worms before his unstoppable might. This is backed up by his slow Villainous Breakdown throughout the fight - he is completely shocked and afraid that the raid is not only staying standing throughout his onslaught, they are winning, even though he's empowered himself with a Titan artifact.
Xal'atath, Blade of the Black Empire has an unusual shape for a weapon - it resembles a sideways "S", with the grip on the inside of one curve, and the blade (of course) on the other. Closer examination, however, reveals that the inner curve of the blade is entirely decorative (for the starter appearance, at least; also the appearance it had before the player empowers it). The outer curve, however, is definitely sharp, and a proper blade. The brilliance? If held "normally", the cutting edge would be towards the wielder, symbolizing that the greatest risk of the weapon is how it will turn on its "owner", or at the least, how it can be (meant to be?) used as a suicidal, sacrificial dagger.
The Stormwind Stockade is the high-security prison of the humans of Stormwind. It is full of torture equipment, such as iron maidens. When the prisoners inevitably riot, the government hires mercenaries (that's you) to kill them. These are the "good guys".
In the Borean Tundra, the players are asked by one of the good guy groups (the Kirin Tor, to be precise) to torture a captured agent of the Blue Dragonflight until he cracks. The Kirin Tor wizard who gives the quest hands you a torture device noted in its description to inflict excruciating pain without causing any physical harm, and that it's made in Dalaran, the Kirin Tor home city. The wizard in turn specifically states that Kirin Tor law forbids them from torturing prisoners... so they hire you, the player, to torture the prisoner with a device made by the Kirin Tor while the wizard observes.
Blood death knights. Just spend a little time trying to figure out how their spells actually work in-game and try not to shudder. Death Strike heals you based on how much damage you've recently suffered. Which means that either the spell is indirectly Cast from Hit Points, or it heals you by sucking your blood back off the floor and shoving it back into your veins. This pales beside Bloodworms though. You summon them and they attack enemies until for a while then die and heal nearby allies. Or to put it another way, you heal people by drenching them in the remains of a haemophagic worm that gorged itself until it exploded. Ew.
So according to lore, dragons are the oldest and wisest of all the mortal races and were charged by the Keepers themselves to protect the aspects of Azeroth. They are also the only sentient species in the game which you can skin, use as a mount, keep as pets, and slaughter by the thousands for no reason whatsoever. (And lest you think all those baby dragon whelplings you killed weren't self-aware yet, a certain tiny blue hatchling would like a word with you.) No wonder Malygos wants to murder us all.
And in Cataclysm, the dragons in the 81-85 zones drop meat that can be cooked into stat-boosting food. It's a wonder most of the Aspects are still on the mortals' side.
Slightly more fridge Squick, but as Alliance when you quest in the Grizzly Hills you accidentally end up eating an important seed out of a bucket. After going through a short chain that involves you using a super-laxative to "retrieve" the seeds you then give them back to the owner. If you stick around a second after handing in the quest, the guy you turned the quest into gives the seeds to his friend to put back, who then responds with "yeah yeah, I know the drill, back in the bucket", now remember the quest text when you first ate the seed, pointing out the "earthy taste"?...
In the raid dungeon Naxxramas there is ambient noise of all types, but a few in particular stand out; a woman wailing "Pleeease!", "Stop, please stop...", "Help me! Save me!", "Please, nooo!". Then you fight this guy◊. Then the crying/screaming stops. You might be thinking, "So what? He just stopped torturing people." Except there were no visible people. He was those people. The fridge horror comes in because typically one doesn't notice the connection at the time. According to an in-game lore character, "Thaddius, built from the flesh of women and children, it is said that their souls are fused together - eternally bound within that foul prison of flesh." Yeah. A video with the sound clips.
Remember the Corrupted Blood Incident? How people would run around infecting others? Yeah. Fridge Horror because people might actually do this in real life. Fun bit of trivia on that, the Corrupted Blood incident is actually used as a case study by scientists and researchers who study infectious diseases and bioterrorism.
Sylvanas' short story. She dies and finds herself in a very unpleasant afterlife. But she says when she last died the afterlife was lovely. Assuming her previous experience wasn't a dying dream this brings a few unsettling possibilities. Now discounting the possibility she didn't just end up their for taking a level in jerkass between deaths there are 2 possible and unpleasant reasons she wound up there. 1) The undead don't get a pleasant afterlife by default 2) Suicide is an instant ticket to crappy afterlife which if you're undead means you don't have much chance of getting to happy heaven without dying in battle or simply being killed in a myriad of accidents or assassinated. This sucks for anyone who doesn't enjoy undeath especially since some newly raised commit suicide in horror. Yes, that's right, die and go to heaven, 5 minutes later be raised as a corpse, freak out and kill yourself and suffer forever. That some forsaken went to their families after they died only to be rejected pretty much means you're out of luck if brought back.
Remember the Greymane Wall? Gilneas built the wall long before the infection of Worgen and told both Alliance and Horde that they wanted nothing to do with the war. Rather than quarantine themselves, their paranoia meant that they effectively barricaded themselves in when the sickness came, keeping all possible aid out. Talk about a security procedure coming back to bite you in the ass.
The Sunwell. When Arthas' march through Quel'thalas blew it up, all of the Blood Elves felt withdrawal from their magical addiction, causing one to draw many parallels between magic and drugs—they even have Bloodthistle, which mimics the effects of magic so well that it's treated as a form of marijuana. When Velen reignited the Sunwell, it was treated as him saving their race—until you remember that they're still magic addicts. He didn't clean them of their addiction, he just gave them a lifetime supply of drugs.
Courtesy of the Discussion page of Wowpedia in relation to what exactly Yogg-Saron being the God of Death means: "Hard to say, for the simple reason that nobody knows what Yogg-Saron is. However there's an important distinction to be made here— the Lich King represents an unbridled power over undeath, while Yogg-Saron appears to personify death. These things are not the same; undeath is unnatural and twisted, while death is in fact a natural and universal phenomenon. My guess is that Yogg-Saron is somehow the literal personification of death itself; the tentacles symbolizing the countless ways death can grasp life, and the maws symbolizing the countless ways death can and will devour life eventually. If this interpretation is true, it would basically mean that Yogg-Saron is the true name and the true face of the Grim Reaper in World of Warcraft." Screw Don't Fear the Reaper, if that WMG is true, you want to avoid the reaper for as long as you can. Even worse when you think of Terenas' last words to Arthas. "No King Rules Forever". Now, where did we hear that being said before? It puts a whole new context to The Nothing After Death Sylvanas and possibly Arthas experienced.
The dwarf starting area has a quest to kill Frostmane troll whelps. While they use the same model as adult trolls, the whelps are roughly the same height as a dwarf - and adult trolls grow to almost twice that. The dwarves (and the player) have been slaughtering what must be the equivalent of troll children. And combined with the fact they're now neutral mobs?
Wrathion's creation. Remember, back in the Badlands, the titan device didn't really "purify" an egg. It took multiple examples of eggs and whelps, cut out the infected parts, and recombined what was left into a single egg. Wrathion is a Frankenstein-style combination of his deceased siblings. Even worse when you realize whelps are sentient even while in the egg.
The Hayward brothers from Gilneas tried to flee Duskhaven by sea. None of them are ever seen again (Although an NPC remarkably familiar to Walt Hayward can be seen at the Teldrassil docks), and it's assumed they died. After you finish the starting zone, the Hayward Fishery is the only place left standing in Duskhaven. So the Haywards would have been completely fine and would have survived if they just stayed there.
In the End Time instance, Murozond says, "I have witnessed the true End Time. THIS? This is a blessing you simply cannot comprehend!" Considering the instance already portrays the Hour of Twilight having come to pass... what exactly did he witness?
Back in Icecrown Citadel, the Death Knight tier vendor was Ormus the Penitent, a former paladin turned death knight who gouged out his own eyes in horror at what he'd done under the Lich King's control. He's also forsworn the use of his dark powers. Unfortunately, death knights who don't cause suffering every so often experience torturous agony and eventually go insane. Ormus never appears again after the raid on Icecrown.
In Warlords of Draenor, Talador's trees are orange except in the Fel corrupted areas. What color are they? The exact same color as in Terokkar Forest. That's right, Terokkar Forest is completely Fel corrupted! Considering Fel consumes life and how both the northeastern half and the southwestern halves of Hellfire are deserts despite the Fel corruption only being in the northeastern portions (The Dark Portal, The Throne of Kil'jaeden, Felspark Ravine, Demon Portals, Pools of Aggonar, Forge Camps and the Path of Anguish), this indicates that Terokkar consumed Tanaan Jungle's life energies. What's even worse is that Nagrand is a lush forest hill area in Warlords of Draenor, yet in Burning Crusade it's a savannah (still green yet much closer to the Barrens than used to be), which indicates that the area is also getting sucked dry of life by Terokkar Forest. That's right; the most beautiful place in Outland turned Tanaan Jungle into Hellfire Peninsulaand is doing the exact same thing to the second most beautiful place.
Taking this line of reasoning one step further, perhaps into the obvious: Fel corruption on that scale has to have come from somewhere. The only source of corruption in the zone itself is Auchindoun, but the desolation there seems to be completely different compared to the forest surrounding it. However, the corruption in nearby Shadowmoon Valley seems more in line, especially taking into account the withered trees there. And unlike Terokkar, there are many sources of fel corruption in that zone. So the corruption isn't native to Terokkar, it's already spread there from SMV... and is spreading further...
Anshal's abilities are terrifying if you pay attention to the implications: Not only can he create plants, but his Soothing Breeze spell heals Anshal and his plants yet silences and pacifies the Raiders. He's suffocating the Raiders with his calm winds.
In Warcraft III, Lord Admiral Daelin Proudmoore has this to say to Jaina about the situation with the orcs: "I understand more than you suspect, my dear. Perhaps in time, you will too." Fast forward to Tides of War and Mists of Pandaria.
Given that the orcs who were interned were the children of the ones who committed the horrible war crimes, and they were forced into those prisons just because of what their parents did, if anything Daelin's reckless attack confirmed a lot of feelings the orcs had, making his actions the biggest Nice Job Breaking It, Hero! in the entire franchise. Even with his death he managed to mess it all up.
In Legion, in the starting Demon Hunter zone, you have to make a Sadistic Choice: kill one of your valuable brethren to power a gateway for needed reinforcements of Red Shirts, or yourself. It turns out that Death Is a Slap on the Wrist in your case, but Illidan himself tells you that you "have an immortal demon soul". Sounds great in theory... except you have given up your essential humanity - or elfity - to defeat the Burning Legion. Congratulations, the only difference between you and Sargeras' troops is which side you're fighting for.
And, to further drive the point home, some of your fellow Demon Hunter NPCs willingly join the Legion once you're past the starting zone.
Some of the stuff you can get from a Bag of Shiny Things and boxes you get from Fishing have frightening implications when you consider they're collected by the Fishing Trainer. There's the Hangman's Noose (dried blood is on it), the Very Unlucky Rock (also stained with blood) and the Polished Skull (no clue as to who it's from). The Crate of Tasty Meat you can buy with Epicurean Awards (which "smells weird" according to the Item Text) can contain creepy Vendor Trash too, like a Rusty Butcher's Knife (blood stained, again) a Motorized Bone Saw ("Best to leave it off," says the text) and a 47" Tapeworm. (The true horror comes when you consider that the useful stuff in the crate is used to make stuff that you - or someone else - is going to eat.)
Another creepy vendor trash is the Rusted Canary Cage, found in the Garrison Mine, an allusion to caged canaries (birds) that miners would carry down into the mine tunnels with them. If dangerous gases such as carbon monoxide collected in the mine, the gases would kill the canary before killing the miners, thus providing a warning to exit the tunnels immediately. while it makes sense that you'd find this here, it's rather common... just how safe is this mine??