History ThatOneBoss / FinalFantasyXIV

** The Cloud of Darkness, the final boss, has a few mechanics in particular. The first is she marks a random DPS with an AOE that constantly triggers for a good 10 seconds. The idea is the marked player has to run away from the party, but sometimes this doesn't happen. The second is there are glowing circles that at least one player has to stand in (the so called "meteor" or "towers" mechanic) to avoid it damaging the entire alliance when it goes off, but this can pop up while a lot of action is going on and some of them may be missed. The last is right after her Ultimate, the parties have to go to particular spots to beat up adds. However, a barrier forms around them that locks whoever's in it and keeps others from attacking it. So it's possible that not enough people can be at an add to kill it.

* [[spoiler:The false Inquisitor Guillaume]] is this primarily because the fight is essentially an EscortMission. The boss himself is pretty standard, but your AI companions ''have'' to survive, and their AI is basically braindead and will get chumped easily unless you take out the boss's adds pronto. Depending on your gear, you may very well need the Echo Enhancement buff to win, and even then it's not a given.

** Cerberus, the second to last boss from the World of Darkness raid, is the only boss from said raid that the community finds hard, even as late as ''Shadowbringers''. This is because the fight operates under a strange phase system where Cerberus is chained and muzzled, but breaks out after a certain point. While muzzled and chained, he hits hard but mostly seems like a typical boss fight, but once he breaks free, he becomes incredibly aggressive and hard to manage. He has several quick attacks such as an attack where he swings his tail at anyone behind him, a problem with DPS naturally, but he also has an attack where he turns around and charges in a straight line. While the tell for it is easy to see, his cast time is fairly quick, so if you realize it too late, he may just hit you anyway. The main gimmick he has that frustrates people however, is his OneHitKill and how to avoid it: at one point, he'll barf out a purple circle, and spawns an enemy called Gastric Acid, which puts the Mini debuff on the player. The idea is that you get hit with Mini, and then stand in the purple circle, at which point he eats your character and you damage his stomach to weaken him so he can be changed again. However, if you don't have Mini and accidentally step in the purple circle, you get stuck and dragged to the center where Cerberus kills you instantly. Due to these factors, its seen as harder then the final boss, the Cloud of Darkness.

* Hrodric Poisontongue, the final boss of the Drowned City of Skalla, is notable in that the attacks coming from the boss itself do not show any orange AOE tell. The player has to figure out what its doing based on its "wind up" animation.
* 4.1 has a rematch against the primal [[spoiler: Lakshmi]], who will constantly spawn orbs of aether that are advancing towoards the [=NPCs=] that are behind you. If one person gets touched by the aether, they become [[BrainwashedAndCrazy tempered by the primal]] and the quest fails. The aether clusters grow in number as the battle goes on and although you have an NPC (and later a second NPC) helping you destroy them, his and your ability to attack the aether are on a short cooldown and can be disastrous if you don't time it right or don't hit the aether when they're bunched up. Unlike other main story quests that give you an Echo buff if you fail and try again, the Echo will ''not'' help you in dealing with the aether clusters.
* Suzaku, the boss of the Hell's Kier Duty, is infamous for the difficulty of said fight. For starters, Suzaku has an opening wipe mechanic in the form of phoenix adds that will target the DPS and start attacking, only to charge a powerful AOE attack that, if not stopped, will do enough damage to wipe all but the most geared tanks. The issue is that right when they spawn, Suzaku turns to the DPS and does an AOE attack, forcing them to scatter. Spellcasting DPS can have seriously trouble killing their add as a result, but that isn't the end of it. The adds are also not cleared from the arena when defeated (this is an important note). After this, Suzaku drops large feathers that start charging an AOE, with the goal being to kill the one in the middle for safety. However, if any of the downed adds from before are in one of the AOE pools, they are revived. The party has to kill any revived adds in a short period of time as Suzaku will cast an AOE that is essentially a party wipe if they aren't killed. If you get past that, you have the very easy section where you need to face the direction the arrow is to get a buff and prevent the boss from gaining any more additional damage. After that however, the arena changes to a donut-shaped arena where you can fall off, with Suzaku having the obligatory knock-back mechanics. However, the main gimmick is Suzaku changes the arena into colored sections then summon a phoenix that flies around the perimeter of the arena. Said phoenix flies into colored symbols that match the colored sections of the arena, which causes whatever symbol the phoenix touched to explode the corresponding section.

** The Idol of Darkness on the seventh floor tended to trip people up with two mechanics. One of them is something the boss does that teleports your character in a certain direction. This isn't so bad the first time around as you just have to make sure you don't fall off the arena. But other times this happens requires you to make sure you teleport in a safe zone due to an AOE about to go off. The second is more of an algamation of mechanics. The gist of it is the boss will send four-columns of bird-things across the arena in a certain order. These birds may go into color-coordinated portals. Naturally you have to remember which teleporter was taken in which order to dodge. Then it has a mechanic where the players are given a light or dark debuff and the birds have a light or dark element to them. The player has to be hit with the opposite color. Which isn't so bad until this combines with the portal mechanic and the debuff you have switches to the other color (so a light-debuffed player has to get hit with a dark elemental bird wave, which gives them a dark debuff). The portal mechanic is dispised by many in the community because it requires micro-managing knowing what portal connects where, what portal the birds went through, which birds went first, and what element ''you'' have, all at the same time.

* Lightwarden Titania, the first Trial boss of ''Shadowbringers'', earned a fairly infamous status not long after the expansion's release. Their abilities when solo are fairly straightforward, with their most dangerous attack in phase one being a wide cleaving tankbuster that can easily cause deaths if the tank isn't paying attention. The ''add phase'', on the other hand... Three adds are summoned and must be killed, except once they are, they're revived with increased size, health, and damage - and the group only has until Titania's Ultimate bar reaches 100 to kill them, or else the party wipes and it's time to start over. Most parties will ''require'' a LimitBreak to deal with the adds in time; the DPS check is ly tight considering Titania's normal mode is fought relatively early in the Shadowbringers story, requiring players to be aware of how to best deal damage while staying mobile enough to deal with the AoE attacks from both Titania and their summoned adds as well as multiple stacking mechanics. The fight is therefore something of a WakeUpCallBoss for newer players who either coasted through older fights with overgeared parties or else boosted their accounts to 70, skipping all the content that came before.

* After fighting your way through the Longstop, Titan awaits, and he's a notorious WakeUpCallBoss. The major problem is his arena is over a fatal fall and many of his attacks involve pushing you off the edge, well outside of the range of any resurrection spells. The arena also shrinks significantly throughout the fight. Hard Mode, at least in its early lifespan, is particularly notorious for Landslide's [=AoE=] flat out lying due to the dodgy hit detection and latency. Two blue lines signify where the ''animation'' will trigger, but not the attack itself. Many a players are subsequently punted off the arena despite seemingly have dodged. In the Extreme version, he now has an arena about the quarter of the size of Normal or Hard, Titan's RingOut attack splits into 3, then 5 lines, he summons additional enemies which do their own Landslide attacks, and he gains a new Shockwave attack that is an Area-of-Effect RingOut if you're too far from him. Oh, and his Granite Gaol attack targets the healers, and if the two healers are too close when trapped, the gaols get a massive defense buff that is basically curtains for them, and soon the rest of the party.

* Thornmarch (Extreme) can be absolute carnage if even one person doesn't know every last aspect of the fight, and the fight itself is complete chaos. Hard mode is relatively simple so the difficulty spike is particularly brutal because not many people expect it to be that difficult. If one of the Mogglesguard goes down, Moggle Mog will revive that member and heal the others from his HP, so focusing on one is out of the question, and they'll keep getting up again and again until Moggle Mog doesn't have the HP to compensate. Every single member of the group will have their role to play, be it interrupting massive [=AOEs=], tanking enemies, nullifying curses and so on, and even a single mistake can cause the entire run to collapse in on itself.
* Ramuh Extreme requires near-perfect coordination, with very little room for error. About 2/3rds of the battlefield is flooded with shin-deep water, which shocks everything inside it whenever a lightning bolt drops (which happens frequently). Ramuh also gains a OneHitKill attack against tanks that requires the Surge Protection buff to survive, and a Taunt attack against everyone else, which must be dispelled before they walk to their death. The second phase of his fight requires you to kill six additional enemies in a circle in just under two minutes tops, otherwise you wipe instantly. Towards the end of the fight, these Arbiters spawn again to charge up Ramuh's OneHitKill to the raid, but are untargetable, giving you a very small window to chunk off the last third of his health, all while dealing with prior mechanics.
* Ifrit Extreme, in addition to several other attack and damage buffs, upgrades his Infernal Nail / Hellfire wipe mechanic from the 4 nails you had to break in Hard Mode (already a difficult task) to '''THIRTEEN'''. In a cruel twist the developers caught on to a Black Mage or Summoner using their Limit Breaks to destroy the nails back in Hard Mode and made it so that the nails explode harmfully when destroyed and cause a stacking damage up debuff of about five seconds in duration. Destroy too many nails too fast and the combination of the damage vulnerability and the explosions wipe the party. Parties are forced to coordinate their speed to be slow enough to not blow up the party, but not so slow that the timer runs out and Ifrit wipes the party with Hellfire.
* Leviathan Extreme, primarily due to the Spinning Dive and Body Slam attacks. These attacks cause knockback, which isn't such a big deal on Hard mode due to the railings around the boat. On Extreme difficulty, however, the railings are torn off by the first tidal wave attack, making it fiendishly easy to get pulled off the boat and permanently removed from the fight. This is only made worse by how short the spout of water (which indicates from which direction Leviathan will attack next) is. Oh, and Spinning Dive slaps anyone hit with it with Water Resistance Down. Mix that in with Briny Veil (forcing healer swaps and requiring the tank holding the tail to run on very little healing) and Grand Fall (a massive, hard-hitting Water-damage AOE that inflicts Heavy), and you have a teeth grinding experience, noted for even giving ''unsynced'' parties trouble two expansions later. When the fight was selected as 5.5's Unreal trial, the encounter had to be ''toned down'' for it to be balanced.
* The final boss of The Keeper Of The Lake, Midgardsormr, while not incredibly difficult, is simply a pain in the ass due to the massive AOE spam coming from the boss and the dragons he revives. Casters will have a very rough time trying to cast anything without having to stop their casting to move out of the way of yet another AOE attack. It's also possible to have multiple AOE attacks cover large portions of the arena, making it much more difficult to dodge them. The worst part is the near instant kill AOE that is tossed out as the fight goes on. In order to not die, you have to kill the add that drops in, causing it to create a barrier that will protect the players from damage. However, if the add spawns in an area where the other AOE attacks are occuring, this can shut down the melee DPS completely, and make it where the Casters have to do the work instead, putting them at risk of not getting it quick enough to help. Furthermore, the other AOEs still have to be avoided, meaning if a player isn't careful, they can die trying to avoid the larger AOE. Not to mention, the overall boss design is so much more different from how most bosses in Duty Finder are that many players struggle with it because they simply are used to dodging whatever boss attacks come their way, not burn down a boss sized HP enemy like this fight.
* [[GetBackHereBoss Vishap]] in The Steps of Faith forces the player to forget everything they’ve learned about how the game’s boss battles work by making the boss move inexorably along a bridge towards Ishgard, requiring precise activation of cannons while holding off a horde of smaller dragons instead of the usual tank-and-spank approach. The entire fight is timed (based on the boss' progression down the bridge), so if the giant dragon reaches the end of the bridge and destroys the final barrier, [[NonStandardGameOver Isghard is doomed to the dragon horde]] and you'll have to redo the entire sequence again. To top it all off, dragon's advancement from beginning to end can take about 10 to 20 minutes and you only have 60 minutes to complete the duty, so each failure puts you at a greater risk for the duty to become {{Unwinnable}}. Unlike other duties, a total party wipe doesn't restart the battle, so even if your group knows that you can't salvage the fight, you're forced to wait for the dragon to destroy the last barrier before you can try again.

* Susano, the level 63 trial, has mechanics that involve good movement and/or positioning to make it easier for other players to handle. For example, one of the mechanics involves marking a player, pushing them back, and forming a line of safety through the marked player and the boss. If the marked player was at an unfortunate position at the time, this can cause the mechanic to damage the rest of the party. This is also when failing mechanics starts applying vulnerability stacks, meaning failing mechanics constantly makes it harder to survive. The Extreme version adds in an extra twist in the second half of the fight, where his ultimate causes him to form a void across the arena, effectively splitting it into two halves. Said void will kill players that stand in it for too long, and Susano will periodically mark players to strike lightning upon them, electrocuting the affected side and taking a chunk of HP out of anyone that gets caught by the aftershock. Later still, those attacks will freeze the player, forcing everyone but the marked player to move to the safe side to avoid taking damage. With all that extra movement, it becomes a metaphorical dance across the arena to avoid killing each other.

* Tsukuyomi Extreme can be a frustrating boss to fight, largely because of one phase. Like normal mode, she has the Lunar phase where the arena will be split into white and black, forcing you to alternate where you stand between the two colors lest you get 5 stacks for standing on one color too long, which kills you. However, unlike normal mode where the field remains 50/50 the whole mechanic, in Extreme, the arena shifts to be about 25/75 in a crescent shape. And at this point, 3 players of the party will be targeted with a marker that will drop an meteor on them. These meteors must be placed in specific spots (well at least one of them must be without anyone else dropping a meteor next to it) or else the party wipes. Who gets said marker is random aside from it always being 1 tank, 1 healer, and 1 dps, and in the confusion, it becomes rather easy for someone to put their meteor in the wrong place and wipe the party. On top of this, all players need to make sure their stacks are currently the smaller color on the field when it gets fully absorbed by the big color, or else they will almost certainly die from getting too many stacks before the (correctly placed) meteor reveals a safe spot to run to. And after doing this phase 2 times, the boss enters a final phase where the boss begins using slash attacks that cover most of the field, and you have to keep track of what the cast bar says (one cast will cover 190 degrees of the arena to her left, the other to her right, and neither cast name explicitly tells you which side is which, you just have to know) and what color she currently is (if she's white, you have to also move away from her as an AoE will go off around her at the same time as the slash, and if she's black, you have to move close to her because an arena filling donut AoE goes off with the slash). And she'll alternate between these attacks and others that are relatively strict as well.

* Lightwarden Titania, the first Trial boss of ''Shadowbringers'', earned a fairly infamous status not long after the expansion's release. Their abilities when solo are fairly straightforward, with their most dangerous attack in phase one being a wide cleaving tankbuster that can easily cause deaths if the tank isn't paying attention. The ''add phase'', on the other hand... Three adds are summoned and must be killed, except once they are, they're revived with increased size, health, and damage - and the group only has until Titania's Ultimate bar reaches 100 to kill them, or else the party wipes and it's time to start over. Most parties will ''require'' a LimitBreak to deal with the adds in time; the DPS check is extremely tight considering Titania's normal mode is fought relatively early in the Shadowbringers story, requiring players to be aware of how to best deal damage while staying mobile enough to deal with the AoE attacks from both Titania and their summoned adds as well as multiple stacking mechanics. The fight is therefore something of a WakeUpCallBoss for newer players who either coasted through older fights with overgeared parties or else boosted their accounts to 70, skipping all the content that came before.

* The boss from the Seat of Sacrifice Trial, [[spoiler: the Warrior of Light Elidibus]]. He has a lot of powerful moves that the player needs to be careful of, ranging from fire debuffs that deal tremendous damage if you move, to summoning a Dragon to attack half of the arena. About a third of the way through the first he employs not one but two mechanics that can easily cause a TotalPartyKill, the first being a button mashing QuickTimeEvent where if even one player fails the entire party dies, followed by him casting a level four limit break where if one of the tanks don't time their level 3 limit just right it is another wipe and right back to the start of the battle. Thankfully after this there is a checkpoint to the fight, though it can be a small mercy considering he adds even more frantic attacks and gets summons that can do even more additional mechanics. The Extreme version of this fight is a different story entirely, though, being a huge exercise in memorization. The players have to remember which Limit Break does what, the elements for Imbued Saber, which summons do what attacks, as well as the infamous Quintuplecast firing off elements in a sequence that must be memorized before they're all set off with no breaks. Oh, and just like the normal version, one poorly timed Limit Break from you can provoke Hallowed Ground, which can potentially be a fatal DPS loss into a wipe by Enrage.

** Hashmal, the second boss, is considered to be the most difficult boss of the entire raid. Many of his attacks can cleave and will probably instantly kill anyone that is not a tank. Hashmal will also charge up an attack that will have one of his arms light on fire and if you are not on the opposite side, his attack will either instantly kill you or do heavy damage and give you a heavily damaging Burns debuff that will kill you after one or two ticks. Hashmal will also summon two pillars that he will cut down and will instantly kill anyone that gets squashed by them. Following that, the boss will bring up a command tower that must be destroyed quickly or his ultimate attack will kill everyone instantly. Not only is this sequence a DPS check, Sand Spheres will also appear as a second DPS check where they will cause heavy damage to the entire alliance if they're not destroyed in time. If more than one Sand Sphere goes off, it's probably an instant wipe. Complicating matters further, Hashmal will also summon two golems that will spam hard hitting AOE attacks that will only grow stronger every time, so the alliance needs to burn them down quickly before everyone dies. It's not unheard of for alliances to use their limit breaks on the golems just to prevent any more damage going out. Uncoordinated parties generally fail here.

* Leviathan Extreme, primarily due to the Spinning Dive and Body Slam attacks. These attacks cause knockback, which isn't such a big deal on Hard mode due to the railings around the boat. On Extreme difficulty, however, the railings are torn off by the first tidal wave attack, making it fiendishly easy to get pulled off the boat and permanently removed from the fight. This is only made worse by how short the spout of water (which indicates from which direction Leviathan will attack next) is. Oh, and Spinning Dive slaps anyone hit with it with Water Resistance Down. Mix that in with Briny Veil (forcing healer swaps and requiring the tank holding the tail to run on very little healing) and Grand Fall (a massive, hard-hitting Water-damage AOE that inflicts Heavy), and you have a teeth grinding experience, noted for even giving ''unsynced'' parties trouble two expansions later.

* The second to last boss of the Delubrum Reginae mini-Alliance Raid, Trinity Avowed, is considered the hardest fight in the raid due to confusing mechanics and short-aoe timers. Her consistently use AOE, Allegiant Arsenal: Bow, is easily telegraphed but the window of time to avoid it is very small compared to what you would expect, making it almost impossible to avoid if you are far enough away from her. The other version of this skill is her summoning copies of herself that attack every tile that she is facing, with only around four spots you can stand on to be safe. The mechanic that makes her super hard though is her [[KillItWithFire Hot]] and [[KillItWithIce Cold]] skill, which causes all players to be marked with a special icon that represents how cold/hot you are. The goal is to make it neutral by standing in the AOE that is the opposite of your temperature but the same amount (so +1 hot means you need +1 cold). The issue is she has three ways of doing this mechanic; the first is a simple case of stand in the AOE, but the second one involves running away after about 90% of the arena is flooded with fire, and you have to move to a specific tile where arrows representing the temperatures will move to. The issue is they don't move in a straight line, instead you have only a split second where the path is laid out to you before they launch, making it easy to simply not know which one you needed to go to because you were unable to see it. The last version involves her raising a sword and swinging it on half of the arena, with each swing having a different elemental type and amount, which is not as hard by comparison, but it can be hard to tell which way the boss will attack because of how her model is designed. The Fury of Bozja mechanic alone is enough to make her one of the hardest fights in the expansion, but the other mechanics, topped with the fact you can only take two hits from a mechanic before being inflicted with Doom and dying, makes it incredibly easy to die.

* Trinity Avowed becomes even ''more'' fun during the Savage version of the fight. For starters, her raidwide attack hits VERY hard and applies a bleed. If you for some crazy reason don't have a pure essence by this point, you WILL die, no level of mitigation will save you. And even with a pure essence, the Aether Shield lost action is all but mandatory for tanks. Beyond that, all of her mechanics from the normal version of the fight return for the savage version, but each mechanic gets a few twists. For starters, all of her weapon change attacks are untelegraphed, so you have to be paying attention to what weapon she draws. And from there, each version of Hot and Cold gets brand new twists:
** For bow, the first change happens before the flame wall even appears. You are given a march debuff, so you must figure out which direction you are going to march, then wait for either the east or west side to have a pillar of flame appear so you can quickly direction your character to march in the opposite direction. The first Arrows mechanic is actually basically the same as normal, but you have a much more complicated ladder grid to figure out than on normal. The second time however, you are given a march debuff that will walk you two panels worth of distance. On top of this, you are also given another debuff on top of your hot/cold debuff that will apply 1 or 2 stacks of hot or cold AFTER you get hit by an arrow. So for instance, if you have 1 hot stack but a debuff with 1 hot stack you have to land on a TWO stack of cold arrow so that when the debuff resolves, you will be reset to zero. This mechanic, generally referred to as math for obvious reasons, applies to the second version of each Hot and Cold mechanic in the fight.
** For staff, the first mechanic largely plays out the same way as normal except you have a forced march in a random direction, so you must figure out which corner has the meteor you need to resolve your hot/cold stacks, then face yourself in the right direction to be marched into the safe spot. For the second iteration of the mechanic, you no longer have forced march, but as above, the math debuff forces you to quickly calculate which meteor you must stand in to get your stacks to zero. On top of this, line AoEs are coming out from multiple directions, so only a specific spot within your meteor is safe to stand in.
** Finally for sword, it is similar to the sword mechanic in that you have to stand on the right side of Trinity Avowed to cleanse your hot/cold stack. However, this time she clones herself into FOUR Trinity Avoweds, each with a different hot or cold strike, which all overlap most of the field. So during this, there are only 5 spots on the map that are safe to stand in. One spot that is hit by none of the Trinity Avoweds, and then 1 spot in each cardinal direction that is hit by only a single Trinity Avowed. If you are anywhere else, you'll get hit by two cleaves and instantly die. And there are no telegraphs until moments before the attack goes out, so you have to figure out where is safe just from which direction each Trinity Avowed is facing and where their swords are facing. And they do this twice in a row, turning in different directions each time, forcing you to figure out again where to stand. And the second time the mechanic happens, the math debuff is applied like with bow and staff. However, with swords, it is very likely you'll get a math debuff that requires you to get hit by a cleave both times (for example, you could start with 1 hot stack and have a debuff that will apply 2 hot stacks. So to resolve your debuff, you'd need to get hit by a two Cold stack cleave with the first attack, then get hit with a one Cold stack cleave with the second attack, leaving you at 2 Cold stacks before the debuff resolves and brings you up to zero stacks.) With all of this going on, even the savage version of the Queen is generally considered to be less of a pain to fight (as long as you have a shot caller who can handle Super Chess.)

* The second to last boss of the Delubrum Reginae mini-Alliance Raid, Trinity Avowed, is considered the hardest fight in the raid due to confusing mechanics and short-aoe timers. Her consistently use AOE, Allegiant Arsenal: Bow, is easily telegraphed but the window of time to avoid it is very small compared to what you would expect, making it almost impossible to avoid if you are far enough away from her. The other version of this skill is her summoning copies of herself that attack every tile that she is facing, with only around four spots you can stand on to be safe. The mechanic that makes her super hard though is her [[KillItWithFire Fury]] of [[KillItWithIce Bozja]] skill, which causes all players to be marked with a special icon that represents how cold/hot you are. The goal is to make it neutral by standing in the AOE that is the opposite of your temperature but the same amount (so +1 hot means you need +1 cold). The issue is she has three ways of doing this mechanic; the first is a simple case of stand in the AOE, but the second one involves running away after about 90% of the arena is flooded with fire, and you have to move to a specific tile where arrows representing the temperatures will move to. The issue is they don't move in a straight line, instead you have only a split second where the path is laid out to you before they launch, making it easy to simply not know which one you needed to go to because you were unable to see it. The last version involves her raising a sword and swinging it on half of the arena, with each swing having a different elemental type and amount, which is not as hard by comparison, but it can be hard to tell which way the boss will attack because of how her model is designed. The Fury of Bozja mechanic alone is enough to make her one of the hardest fights in the expansion, but the other mechanics, topped with the fact you can only take two hits from a mechanic before being inflicted with Doom and dying, makes it incredibly easy to die.

* The second to last boss of the Delubrum Reginae mini-Alliance Raid, Trinity Avowed, is considered the hardest fight in the raid due to confusing mechanics and short-aoe timers. Her consistently use AOE, Allegiant Arsenal: Bow, is easily telegraphed but the window of time to avoid it is very small compared to what you would expect, making it almost impossible to avoid if you are far enough away from her. The other version of this skill is her summoning copies of herself that attack every tile that she is facing, with only around four spots you can stand on to be safe. The mechanic that makes her super hard though is her [[KillItWithFire Fury]] of [[KillItWithIce Bozja]] skill, which causes all players to be marked with a special icon that represents how cold/hot you are. The goal is to make it neutral by standing in the AOE that is the opposite of your temperature but the same amount (so +1 hot means you need +1 cold). The issue is she has three ways of doing this mechanic; the first is a simple case of stand in the AOE, but the second one involves running away after about 90% of the arena is flooded with fire, and you have to move to a specific tile where arrows representing the temperatures will move to. The issue is they don't move in a straight line and you don't have line to find out which one you need. The last version involves her raising a sword and swinging it on half of the arena, with each swing having a different elemental type and amount. The Fury of Bozja mechanic alone is enough to make her one of the hardest fights in the expansion, but the other mechanics, topped with the fact you can only take two hits from a mechanic before being inflicted with Doom and dying, makes it incredibly easy to die.

** The Thunder God in the Orbonne Monastery has a sheer number of mechanics that can catch many first time players off guard. He starts the fight with Cleansing Strike, which brings the entire alliance down to [[HPToOne just 1 HP]] and inflicts Doom, which will kill everyone in 10 seconds unless they are healed back to max HP. The boss also auto attacks all of the tanks at once constantly, so healers from every alliance have to keep on top of healing their tanks. The Thunder God will then use several attacks which requires players to be positioned in certain ways; he can either attack the outermost portion of the arena, the innermost portion of the arena, attack one whole section (circular areas) of the arena, or attack whole sections one by one. Next up, his Crush Weapon attack will mark someone and they have to constantly run away as the attack will follow them and hit multiple times, which will kill the player in 2 or 3 hits if they can't avoid it. Crush Helm has all the tanks suffer Magic Vulnerability Up, which makes the next attack very likely to kill them unless the tanks have their defensive moves popped up and/or the healer removes the debuff in time. Another attack the boss has needs everyone to stand in a circle (3 per circle) to minimize damage from his next attack, which will get a damage increases if there are not enough people standing in the circles. Another attack he'll use involves a mechanic similar to Ozma where the boss will drop an AOE circle on a player and if the circles touch each other, the entire alliance will get hit for big damage and a bleeding debuff. He has a tether attack that contrary to what might seem logical cannot be grabbed by the tank. It is a multi-hitting attack that applies a defense down buff, and one to two stacks of it will cause the tank to be melted by the boss's auto attacks. It has to be passed between the DPS and healers between each strike to be successfully handled. Lastly, the boss will use Crush Accessory where the entire platform is covered in damaging ice and each alliance then has to kill the Icewolves that appear or they'll explode for massive alliance-wide damage. Needless to say, the Thunder God quickly grew notorious for being a PUG killer.

* Much like The World of Darkness in the Crystal Tower raids, Dun Scaith holds a special place in the Void Ark raids for having more bosses than not that are That One Boss.
** Deathgaze, the first boss, is fought on an airship and the first thing it does as part of its introduction is ''knocking off the rails''. Naturally this means you can fall off. Also naturally this means it'll do attacks that push you back. In addition, there are several instant death mechanics that have to be avoided and the boss has a time limit to kill.
** The second boss, Ferdiad Hollow, has mechanics that are fitting for its jester getup. The first is it summons Atomoses, with one or two of them tethered to a blue orb or a golden donut. The Atomos(es) will then suck them up and spit them back out on a corresponding one of the same color. You have to avoid the blue orb but stay in the golden donut. The second major one that trips up people up is Ferdiad will apply an elemental debuff and start casting an elemental raid-wide attack. Then 12 circles dot the arena that can enhance or reduce the attack's effectiveness, depending on their color and their colors swap if someone steps on them. Cue a bunch of people stepping on them thinking this does something with the people who know how the mechanic works yelling at the alliance to stop stepping on them.
** Scathach, the penultimate boss, has an alliance wipe mechanic in the form of an add. If this add isn't killed fast enough, that's it for the fight. Her other mechanics can be tricky to perform without issue, such as one that cleaves two quarters of the arena and the only way to tell which two quarters is by how her "hair" is positioned.
** Diabolos, the last boss. The boss which immediately precedes him would have probably been on this list as well, however, once Diabolos enters his second phase, Diabolos Hollow, he begins to copy her attack pattern only ramped UpToEleven. To make things worse, for the first part of the battle, Diabolos Hollow has complete damage immunity and guaranteed critical hits. If that wasn't bad enough early in the patch's life people didn't realize the immunity functioned like Stoneskin and required them attack until it broke.

** Speaking of Alexander Prime, the last boss of the Alexander raid series is notable in that you ''need'' to use a Level 3 tank limit break to survive its Ultimate on the ''normal'' difficulty. And it needs to be timed just right, otherwise the effect will wear off and you'll have a party wipe anyway. There's also the "Timegate" mechanic that puts players into a 1v1 scenario with a {{Mook}}; if even one of those players dies, it's probably a wipe. The Savage version manages to catch up with Savage Cruise Chaser's difficulty based on his sheer damage output on top of all this: everything that isn't Alexander Prime's auto-attack will do between 20k and ''50k'' damage unmitigated, several of these are tank busters that are '''used in combos with each other''', and ''all'' of said tank busters are cleaves[[note]]the attack will hit multiple party members if it is pointed at them[[/note]].

* In a classic case of BeCarefulWhatYouWishFor, the "we want Ozma (Savage)" meme that some of the playerbase agreed with reached its logical conclusion when we did indeed get Ozma (Savage). Proto Ozma, the final boss of the already-brutal Baldesion Arsenal, takes and scales up all of the mechanics from its predecessor from the Weeping City of Mhach[[note]]the only change is that the Cube's exploding orbs are now a Tank mechanic, as Baldesion Arsenal can have more than three Tanks)[[/note]] and then adds a few more to the mix. The first is a new transformation, "Stellation" (star), that does not follow the aggro table and requires the party to stack for its auto-attacks, and has an attack that deals heavy knockback on what is already a narrow fighting arena. Second, Ozmashades will periodically spawn at the back of the platforms and perform one of the three transformation attacks in conjunction with Proto Ozma's attacks, creating some vicious mechanics dances. Last but certainly not least, the base Sphere form is no longer a breather phase, capable of shaving half of the Main-Tank's HP off with a single auto-attack, and more importantly requiring ''everyone'' to stand on buttons around the arena to get a buff so that Proto Ozma's Black Hole doesn't '''evict people from the dungeon'''. This is especially painful due to Baldesion Arsenal's limit to how many boss attacks you can be hit by and its restriction on revive skills, so if you're dead when Sphere comes up, you're screwed. And if one of the buttons goes unpressed, '''everyone''' is screwed.

** Mateus, the first boss, requires the teams to play out their parts in different portions of each phase. A lot of people coming into the raid are used to simply mowing down the boss and only occasionally going back to their markers to do something. This fight requires that each party do something at different points, otherwise it makes continuing the fight practically impossible. The second phase has a gimmick where everyone gets a debuff that stacks over time, with 9 stacks resulting in death. To reset it, players need to kill adds. Players here either forget to reset the stack or not focus on the adds. The third phase also requires each party to coordinate in order to not induce an ''alliance'' wipe.

* Omega raid series:
** Halicarnassus in Deltascape V3.0 (Savage) is one hell of a wake-up call for hardcore raiders. Alte Roite and Catastrophe were hard-hitting but ultimately easy-to-learn bosses that didn't have too much HP, luring new players into a false sense of security before Halicarnassus painfully demonstrates what a DifficultySpike is. Whereas the preceding bosses took some time to get going, Hali takes all of a few seconds to start the fight with a devastating CriticalHit tank buster[[note]] which [[ExactlyWhatItSaysOnTheTin always crits]] if the tank isn't using the role skill that negates it, doing a whopping 72k damage before mitigation or vulnerability[[/note]] immediately followed by [[ThatOneAttack Spellblade Holy]].[[note]] which in Savage places several [=AOE=] markers and one stack marker on players and then ''stuns them and swaps their positions'' before the [=AOEs=] land, instantly wiping the raid if players are positioned wrong[[/note]] The fight only gets worse from there with her multiple "game board" arenas and her Queen's Waltz attack which changes its properties depending on the current board, culminating in a final phases with tiles from ''all'' the boards and her jumping around them to determine the Waltz's effect.
** The Phantom Train in Sigmascape V1.0 (Savage) is noted for being a morale draining fight. Much of it has to do with a complex string of mechanics that's RNG heavy, often leaving no room for error. Two of them suck away a player for a non-trivial amount of time. At least for a player death they can get back in the fight within seconds, screwing up the one mechanic that gets players whisked away means they're out of the fight for at least a minute which is a huge DPS loss. And the DPS requirements for the boss are ''very'' tight, so you can afford very few screw ups.
** The normal version of Omega has served as a rather difficult challenge for the average player. It has many hard hitting attacks and requires a fair amount of area awareness. But it's most infamous move is the Wave Cannon, a laser attack that covers about 200 degrees of the area around Omega on either it's right or left side. And the only way to know which side is getting blasted is whether it casts "Starboard Wavecannon" or "Larboard Wavecannon". Even ignoring that "Larboard" isn't used anymore in favor of "Port", if you aren't familiar with your nautical directions, you are in for a ''world'' of hurt, as the attack markers on the ground only appear for a split second before damage goes out, mostly to let you know whether you succeeded or failed the mechanic before it goes out. And the worst part is the attack flips the boss 180 degrees before it casts the attack again in a random direction, so you have to be able to figure out where the boss's right or left is twice in quick succession.

** Garuda and Ifrit on the sixth floor, especially in Savage mode. Much of the problem is that Garuda makes it so you can't be near her or screws with positioning and Ifrit has a tendency to move around a lot. While casters have an easier time with this fight (but not by much), melee will have a grand time trying to land optimal hits and keeping up with their rotation.

** The Shadowkeeper, the 10th floor of the raid, brings back the "cleave half the arena" mechanics, but with a twist. It can also spawn a shadow which actually does the cleaving. So not only do you have to figure out what the boss is going to do, you have to figure out if a shadow spawned, where it's at, and the proper direction based on it to stand in. It doesn't help that at first glance, it's hard to tell where the front of the shadow is in order to orient yourself properly. Obviously this gets ramped up in Savage mode where the direction the cleave is coming requires looking at the boss rather than the attack name (Normal mode does say which direction the cleave is going out).

* [[spoiler:Warrior of Light, Elidibus]] is the trial of 5.3 and by extension FinalBoss of the Warrior of Darkness chapter and he more than proves a challenge, with incorporating a multitude of mechanics, some of which were rarely used before the fight, in addition to his own. About a third of the way through the first he employs not one but two mechanics that can easily cause a TotalPartyKill, the first being a button mashing QuickTimeEvent where if even one player fails the entire party dies, followed by him casting a level four limit break where if one of the tanks don't time their level 3 limit just right it is another wipe and right back to the start of the battle. Thankfully after this there is a checkpoint to the fight, though it can be a small mercy considering he adds even more frantic attacks and gets summons that can do even more additional mechanics. The Extreme version of this fight is a different story entirely, though, being a huge exercise in memorization. The players have to remember which Limit Break does what, the elements for Imbued Saber, which summons do what attacks, as well as the infamous Quintuplecast firing off elements in a sequence that must be memorized before they're all set off with no breaks. Oh, and just like the normal version, one poorly timed Limit Break from you can provoke Hallowed Ground, which can potentially be a fatal DPS loss into a wipe by Enrage.

* [[spoiler:The false Inquisitor Guilleman]] is this primarily because the fight is essentially an EscortMission. The boss himself is pretty standard, but your AI companions ''have'' to survive, and their AI is basically braindead and will get chumped easily unless you take out the boss's adds pronto. Depending on your gear, you may very well need the Echo Enhancement buff to win, and even then its not a given.
* Siren is absolute hell for anyone playing the role of a healer. Siren herself doesn't deal too much damage, but the zombies that she summons can quickly mess up anyone if they're not healed fast enough. Siren also has the ability to inflict the Charm status on a random person that can't be cured with Esuna; the only way to get rid of Charm is to have the target's HP completely filled, which means spamming Cure spells. If you fail to remove Charm, then the effect changes where the target loses control over themselves and they attack the party for a few seconds. It's not bad if a magic user is affected since they have weak physical attack power, but god help you if a high damage dealing player gets affected by Charm. To make matters worse, Siren can also cause Reduced Immunity, which makes healing magic less powerful for the affected players. And yes Siren WILL cause Reduced Immunity on top of Charm as well.
* Captain Madison for Satasha Hard can be hell for even parties that are prepared. Madison will sometimes pick a random party member and shoot them until they die, then switching to another target. Rinse and repeat. Madison will get a damage boost for his gun spam, which makes healing though it impossible. Only by having the party damage him enough until he stops will work, but if your party isn't properly geared or aware, then it's a guaranteed wipe.
* Feridad, the final boss of Adampor Keep (Hard). At first the fight is simple, but soon you find out the main gimmick of the fight, that he summons adds tethered to him that expands the range of his AOE attack which pretty much kills everyone except the Tank. While the first time is pretty easy to avoid, you are not out of the woods yet, he then spawns a slime add on a player that prevents them from moving and needs to be killed before he can do a OneHitKill attack to that party member. Then while attacking he uses several line AOEs at the same time as summoning a couple of energy scythes that track party members and can easily kill them. And if that wasn't painful enough he does his expanding AOE again, this time with a single very bulky add, and also a couple of the slime adds pinning half the party in place. It gets so bad that most DPS just use their limit break on the bulky add.
* The mechanic of The Lost City of Amdapor's last boss, Diablos, is to hide away in another dimension while it does a highly damaging AOE that applies a debuff stack. Sounds easy, until you realize the only way to get in this other dimension is to open a pair of doors withc matching symbols. Okay, still doesn't sound so bad. But then those symbols are only visible for the first 15 seconds of the fight, and they're ''randomized'' per pull. While a sufficiently skilled party can ignore this mechanic, trying to do this fight properly definitely puts it in this territory.

* Thornmarch (Extreme) can be absolute carnage if even one person doesn't know every last aspect of the fight, and the fight itself is complete chaos. Hard mode is relatively simple so the difficulty spike is particularly brutal because not many people expect it to be that difficult. If one of the Mogglesguard goes down, Moggle Mog will revive that member and heal the others from his HP, so focusing on one is out of the question, and they'll keep getting up again and again until Moggle Mog doesn't have the HP to compensate. Every single member of the group will have their role to play, be it interrupting massive AOEs, tanking enemies, nullifying curses and so on, and even a single mistake can cause the entire run to collapse in on itself.
* Ramuh Extreme requires near-perfect coordination, with very little room for error. About 2/3rds of the battlefield is flooded with shin-deep water, which shocks everything inside it whenever a lightning bolt drops (frequently). Ramuh also gains a OneHitKill attack against tanks that requires the Surge Protection buff to survive, and a Taunt attack against everyone else, which must be dispelled before they walk to their death. The second phase of his fight requires you to kill six additional enemies in a circle in just under two minutes tops, otherwise you wipe instantly. Towards the end of the fight, these Arbiters spawn again to charge up Ramuh's OneHitKill to the raid, but are untargetable, giving you a very small window to chunk off the last third of his health, all while dealing with prior mechanics.

** Diabolos in Dun Scaith. The boss which immediately precedes him would have probably been on this list as well, however, once Diabolos enters his second phase, Diabolos Hollow, he begins to copy her attack pattern only ramped UpToEleven. To make things worse, for the first part of the battle, Diabolos Hollow has complete damage immunity and guaranteed critical hits. If that wasn't bad enough early in the patch's life people didn't realize the immunity functioned like Stoneskin and required them attack until it broke.

* Susano, the level 63 trial, has mechanics that involve good movement and/or positioning to make it easier for other players to handle. For example, one of the mechanics involves marking a player, pushing them back, and forming a line of safety through the marked player and the boss. If the marked player was at an unfortunate position at the time, this can cause the mechanic to damage the rest of the party. This is also when failing mechanics starts applying vulnerability stacks, meaning failing mechanics constantly makes it harder to survive.

* The Chrysalis trial has two notable mechanics that causes problems if the party isn't aware of what to do. The first is the boss summons red and black orbs that the players have to pop before they reach the boss. However, popping an orb throws on a stacking debuff that gets overridden if they pop an orb of the other color. While this sounds easy in theory, the orbs spawn randomly so a situation where several orbs of the same color spawn close to where you are. The second mechanic requires the tanks to soak meteors while the DPS has to take down an add. The problem comes in that the meteors do ''a ton'' of damage upon taking them, which is why the tanks have to soak them. Naive non-tank players may think they can help by soaking them, only to die. The other is that often times the add requires an LB3 to take down fast enough before the tanks die from attrition due to the meteor soaking.

** The 11th floor has Fatebreaker, whose fight consists of gimmicky mechanics with almost no "standard" mechanics. The gist of it is they indicate an element they're using, followed by the attack itself. This starts of as a combination of three possible mechanics and two elements. But halfway through the fight it adds a third element (though it only affects two of the mechanics). And the elements chosen more or less randomly, so you have to pay attention to what element its using prior to the mechanic, which can be easily overlooked if you're tunnel visioning or there's a ton of stuff going on. In addition it brings back the mechanic from Mist Dragon where it obscures the arena and you have find a safe spot by running around the arena, finding out where it's at (Fatebreaker won't be visible unless you're basically on the edge of the arena close to it), and standing where it's not at.

** Angra Mainyu. Oh boy, where to start. The first gimmick is the boss does an arena wide AOE where half the arena is light and the other half is dark. At first it doesn't matter which side you stand on. However, this applies a debuff that increases the damage if you stand in the same side again and it'll be a while before its cast again leading to players forgetting which one they stood in (the debuff also isn't too obvious about where you stood in). The second is the boss often shoots out a wide laser beam that causes a lot of damage to anyone not a tank. If the main tank isn't good about staying still or the tanks are fighting for aggro, this causes the boss to wildly shoot this laser, potentially hitting a good number of the alliance. Then there's a look-away doom mechanic that often gets overlooked due to how much is going on and can only be cured by standing in one of the glowing circles. Another mechanic that's instant death involves one player being marked and if a multiple of 3 players are standing in close proximity, they all die when the cast goes off. And finally there are adds that need to be killed, otherwise they explode and do massive damage to the alliance. It's telling one of the ''easiest'' mechanics to do is Roulette, an often derided ability in other Final Fantasy games, which simply marks a quarter of the arena for instant death and if done properly, is easy to dodge.

* Cerberus, the second to last boss from the World of Darkness raid, is the only boss from said raid that the community finds hard, even as late as ''Shadowbringers''. This is because the fight operates under a strange phase system where Cerberus is chained and muzzled, but breaks out after a certain point. While muzzled and chained, he hits hard but mostly seems like a typical boss fight, but once he breaks free, he becomes incredibly aggressive and hard to manage. He has several quick attacks such as an attack where he swings his tail at anyone behind him, a problem with DPS naturally, but he also has an attack where he turns around and charges in a straight line. While the tell for it is easy to see, his cast time is fairly quick, so if you realize it too late, he may just hit you anyway. The main gimmick he has that frustrates people however, is his OneHitKill and how to avoid it: at one point, he'll barf out a purple circle, and spawns an enemy called Gastric Acid, which puts the Mini debuff on the player. The idea is that you get hit with Mini, and then stand in the purple circle, at which point he eats your character and you damage his stomach to weaken him so he can be changed again. However, if you don't have Mini and accidentally step in the purple circle, you get stuck and dragged to the center where Cerberus kills you instantly. Due to these factors, its seen as harder then the final boss, the Cloud of Darkness.

* Hrodric Poisontongue, the final boss of the Drowned City of Skalla, is notable in that half of the bosses mechanics do not show any orange AOE tell. The player has to figure out what its doing based on its "wind up" animation. This is on top of [=AOEs=] that drop on players in various combinations.

* Red Comet, the Red Chocobo from Bozja, is the absolute bane of the Southern Front. Every one of its attacks is a potential OneHitKill, and the [=AOEs=] of its attacks are ''everywhere'', giving very little room to dodge without getting blasted to the Seven Hells and back. Players who know how to fight it still fear it, and anyone going into it blind is likely going to die repeatedly. Using Reflect can protect you from most of its attacks, but you'll still gain stacks of Vulnerability Up every time you are hit, making you into a GlassCannon if you get hit when you're not under Reflect. ''However'', if you want a chance at dueling Lyon, you have to do those mechanics correctly and not get a single Vulnerability Up stack at all, so cheesing it with Reflect is out of the question.

* Red Comet, the Red Chocobo from Bozja, is the absolute bane of the Southern Front. Every one of its attacks is a potential OneHitKill, and the [=AOEs=] of its attacks are ''everywhere'', giving very little room to dodge without getting blasted to the Seven Hells and back. Players who know how to fight it still fear it, and anyone going into it blind is likely going to die repeatedly. Using Reflect can protect you from most of its attacks, but you'll still gain stacks of Vulnerability Up every time you are hit, making you into a GlassCannon if you get hit when you're not under Reflect.

* The Mist dragon, the last boss of the 4.4 dungeon The Burn, can be pretty tough for a dungeon boss. It has Several Aoes which can be difficult to dodge and will freeze you if caught in it, requiring another player to break you out on top of placing Vulnerability on you. He also makes ice circles on the ground which stick around for a while that usually target the tank, which limits the space you can move, and it can swoop across the arena in random direction giving you little warning in what direction it will come from save for highlighting the area, but only if you are close to that spot, and will freeze anyone caught in it, after which he immediately follow this up with a proximity attack so if you aren't very quick about freeing players and getting out the way chances are some of your characters will go down and god help you if there's no one who can revive them. It also has a DPS check where it vanishes and three Dragon heads appear that slowly engulf the platform in an AOE. If you do not kill them quick enough, the entire party will be frozen and die, not helping of which is the fact that if you accidentally attack the boss during it, he takes no damage, and you get hit with a debuff and your own attack as punishment.

A [[RunningGag party-wipingly]] popular MMO needs good bosses to challenge these adventurers, and these here are some of the more notorious cases.

'''(Page is under construction)'''

* For quite a few, the primal [[WakeUpCallBoss Titan]] counts. The major problem is his arena is over a fatal fall and many of his attacks involve pushing you off the edge, well outside of the range of any resurrection spells. The arena also shrinks significantly throughout the fight. Hard Mode, at least in its early lifespan, is particularly notorious for Landslide's [=AoE=] flat out lying due to the dodgy hit detection and latency. Two blue lines signify where the ''animation'' will trigger, but not the attack itself. Many a players are subsequently punted off the arena despite seemingly have dodged. Basically, Titan will ''not'' allow you to cut it close.
* Garuda deserves a mention. Her attacks are absolutely brutal for melee DPS, and to make matters worse, she has a particularly large cleave. About a third into the fight, she will begin summoning feathers that explode for considerable damage. A short while thereafter, two adds will spawn, each with their own scaled down versions of all her attacks. If both aren't killed quickly, Garuda will wipe the party. Ironically, her Hard Mode counterpart is painfully easy by comparison.
* Coming right before Titan in terms of dungeons and trials is the last boss of [[ThatOneLevel Brayflox's Longstop]], Aiatar. In addition to using poison debuffs liberally throughout the fight, it also spams a poisons AOE pool that will quickly overtake the battleground. Leaving the boss on the pools will have its HP regenerate.

* Cerberus, the second to last boss from the World of Darkness raid, is the only boss from said raid that the community finds hard, even as late as ''Shadowbringers''. This is because the fight operates under a strange phase system where Cerberus is chained and muzzled, but breaks out after a certain point. While muzzled and chained, he hits hard but mostly seems like a typical boss fight, but once he breaks free, he becomes incredibly aggressive and hard to manage. He has several quick attacks such as an attack where he swings his tail at anyone behind him, a problem with DPS naturally, but he also has an attack where he turns around and charges in a straight line. While the tell for it is easy to see, his cast time is fairly quick, so if you realize it too late, he may just hit you anyway. The main gimmick he has that frustrates people however, is his OneHitKill and how to avoid it: at one point, he'll barf out a purple circle, and spawns an enemy called Gastric Acid, which puts the Mini debuff on the player. The idea is that you get hit with Mini, and then stand in the purple circle, at which point he eats your character and you damage his stomach to weaken him so he can be changed again. However, if you don't have Mini and accidentally step in the purple circle, you get stuck and dragged to the center where Cerberus kills you instantly. Due to these factors, its seen as harder then the final boss, the Cloud of Darkness.

* While all of the [[BonusBoss Extreme versions of Primal fights]] are this to an extent, there are some standouts:
** Titan Extreme. Along with the things listed above, he now has an arena about the quarter of the size of Normal or Hard, Titan's RingOut attack splits into 3, then 5 lines, he summons additional enemies which do their own Landslide attacks, and he gains a new Shockwave attack that is an Area-of-Effect RingOut.
** Thornmarch (Extreme) can be absolute carnage if even one person doesn't know every last aspect of the fight. Hard mode is relatively simple so the difficulty spike is particularly brutal because not many people expect it to be that difficult. Every single member of the group will have their role to play, be it interrupting massive AOEs, tanking enemies, nullifying curses and so on, and even a single mistake can cause the entire run to collapse in on itself.
** Ramuh Extreme requires near-perfect coordination, with very little room for error. About 2/3rds of the battlefield is flooded with shin-deep water, which shocks everything inside it whenever a lightning bolt drops (frequently). Ramuh also gains a OneHitKill attack against tanks, and a Taunt attack against everyone else, and the second phase of his fight requires you to kill six additional enemies in a circle in just under two minutes tops, otherwise you wipe instantly. Towards the end of the fight, these Arbiters spawn again to charge up Ramuh's OneHitKill to the raid, but are untargetable, giving you a very small window to chunk off the last third of his health, all while dealing with prior mechanics.
** Ifrit Extreme, in addition to several other attack and damage buffs, upgrades his Infernal Nail / Hellfire wipe mechanic from the 4 nails you had to break in Hard Mode (already a difficult task) to '''THIRTEEN'''. In a cruel twist the developers caught on to a Black Mage or Summoner using their Limit Breaks to destroy the nails back in Hard Mode and made it so that the nails explode harmfully when destroyed and cause a stacking damage up debuff of about five seconds in duration. Destroy too many nails too fast and the combination of the damage vulnerability and the explosions wipe the party. Parties are forced to coordinate their speed to be slow enough to not blow up the party, but not so slow that the timer runs out and Ifrit wipes the party with Hellfire.
** Leviathan Extreme, primarily due to the Spinning Dive and Body Slam attacks. These attacks cause knockback, which isn't such a big deal on Hard mode due to the railings around the boat. On Extreme difficulty, however, the railings are torn off by the first tidal wave attack, making it fiendishly easy to get pulled off the boat and permanently removed from the fight. This is only made worse by how short the spout of water (which indicates from which direction Leviathan will attack next) is. Oh, and Spinning Dive slaps anyone hit with it with Water Resistance Down. Mix that in with Briny Veil (forcing healer swaps and requiring the tank holding the tail to run on very little healing) and Grand Fall (a massive, hard-hitting Water-damage AOE that inflicts Heavy), and you have a teeth grinding experience, noted for even giving ''unsynced'' parties trouble two expansions later.

* Cuchulainn, the third boss of the Void Ark, is already shaping up as being this. On top of inflicting an uncurable debuff that will slowly but surely sap away at the players' health, he possesses a very wide, lingering AOE that will kill any player caught in it in a manner of seconds (God help you if he accidentally drops one of these on the platforms you need to stand on to avoid his instant-kill attack !), will spawn adds that he can absorb for a significant damage boost, orbs that will need to be exploded before they can explode on their own, often wiping out the raid, or towers that will worsen the constant damage taken by everyone and need to be taken out fast. On top of all this, he boasts a high amount of health and can make himself invincible in certain phases, making him a very grueling MarathonBoss. Compared to him, the actual last boss of the raid is a cakewalk.

** Quickthinx Allthoughts, leader of the Goblin Illuminati, engages you personally in Alexander: The Arm of the Son (Midas' third floor). The fight's difficulty comes from the sheer number of mechanics everyone needs to know. First off, he has four cages around the arena that Quickthinx drops players into, each with their own gimmick that has to be followed, or someone/everyone will die. Healers can't target people blocked off by the cages, and anyone too close to the abductee gets taken with them, which almost always ends in a wipe. Self-destructing adds also spawn during this and have to be burned down before the go off. Secondly, Quickthinx will constantly fire off party-wide damage moves, one of which is as laser with no AOE marker. Third, Quickthinx's pet cat will periodically waltz into the arena and spawn a "True Heart" which, if not destroyed before it reaches Quickthinx, will severely boost his AOE power to lethal levels, forcing the Tank to drag him around the arena so the Heart doesn't reach him. He also drops giant iron balls during this phase that do a painful 9999 damage to anyone they touch, forcing constant dodging. Fourth and finally, his "Uplander Doom" attack stacks vulnerability on the current main Tank, forcing frequent tank-swapping -- not normally an issue, but he has a bad habit of doing this when the cat and iron balls are out, which can lead to keyboard/controller/whathaveyou-breaking moments if the iron balls happen to get between the off-tank and Quickthinx before he can take aggro. The whole party has to be on its toes for the whole fight, or Quickthinx can cause a wipe with little warning. Lots of players quickly called it the hardest fight of Midas, and some are just ''dreading'' what the Savage version will be like...
* Remember Ozma, the murderous marble BonusBoss from ''VideoGame/FinalFantasyIX''? 3.3 brings it back as the penultimate boss of the Weeping City of Mhach, and it is every bit as brutal now as it was then. It rains [=AOEs=] on the party like they're going out of style, it occasionally sticks players with a bomb debuff that is a OneHitKill if they do ''anything'' while they have it, adds will drop in as AOE meteors that need to be carefully place and killed before they self-destruct for raid-wide damage, one of Ozma's forms has exploding energy balls that need to be soaked up by the tanks before ''they'' self-destruct for raid-wide damage, and [[ArsonMurderAndJaywalking it's possible to fall off of the arena]] (thankfully Ozma itself can't kick you off, but you can walk off yourself, so gap-closing skills like Jump and Shoulder Tackle need to be used with care). A single mistake is enough to wipe a whole party, which quickly snowballs into wiping the whole alliance. Its signature Doomsday attack is ironically the ''easiest'' mechanic to deal with since it's only used for a DPS check.
* The boss who immediately follows Ozma, Calofisteri. While her pattern and mechanics are much easier to read and predict than Ozma's, she offsets this with her massive range (the entire arena to whichever side of her that her blade is on), her extremely fast casting times (giving players little time to avoid it), and the '''huge''' amount of damage she causes. Now add in the fact that she is constantly planting traps around the arena which can end up forcing unlucky players to get hit by her powerful Haircut attack and you have a boss who ends up getting a higher kill record than Ozma in many cases.

* Cruise Chaser in Alexander: The Heart of the Creator, while unanimously a fun boss with a fun theme, can still be maddeningly difficult due to the coordination the party needs to survive. A large number of his attacks are [=AOEs=], and he can throw out two of them at the same time, or even ''three'' in the later phases of the fight, so anyone unprepared to move at a moment's notice is likely to be killed - and some of these [=AOEs=] are targeted directly at players, so anyone standing beside them is likely to die too. He also spawns several types of exploding adds: a robot buddy that detonates for ''huge'' party-wide damage if it isn't burned down quickly, a pair of canister bombs that can't be destroyed and instead must be hid behind to avoid a mass [[StandardStatusEffects confusion]] attack and will eventually explode for unavoidable damage, and a bunch of "Lapis Lazuli" orbs that must be burned down before he casts his SignatureMove (while also throwing out a [[HPToOne Photon]] before said Signature Move for good measure). Cruise Chaser's ([[BonusBoss optional]]) Savage incarnation is considered even harder than Savage Alexander Prime, exchanging the exploding canisters for ''double'' the [=AOE=] patterns.
* Speaking of Alexander Prime, the last boss of the Alexander raid series is notable in that you ''need'' to use a Level 3 tank limit break to survive its Ultimate on the ''normal'' difficulty. And it needs to be timed just right, otherwise the effect will wear off and you'll have a party wipe anyway. There's also the "Timegate" mechanic that puts players into a 1v1 scenario with a {{Mook}}; if even one of those players dies, it's probably a wipe. The Savage version manages to catch up with Savage Cruise Chaser's difficulty based on his sheer damage output on top of all this: everything that isn't Alexander Prime's auto-attack will do between 20k and ''50k'' damage unmitigated, several of these are tank busters that are '''used in combos with each other''', and ''all'' of said tank busters are cleaves[[note]]the attack will hit multiple party members if it is pointed at them[[/note]].
* Diabolos in Dun Scaith. The boss which immediately precedes him would have probably been on this list as well, however, once Diabolos enters his second phase, Diabolos Hollow, he begins to copy her attack pattern only ramped UpToEleven. To make things worse, for the first part of the battle, Diabolos Hollow has complete damage immunity and guaranteed critical hits. If that wasn't bad enough early in the patch's life people didn't realize the immunity functioned like Stoneskin and required them attack until it broke.
* For the hardcore raiders, Halicarnassus in Deltascape V3.0 (Savage). Alte Roite and Catastrophe were hard-hitting but ultimately easy-to-learn bosses that didn't have too much HP, luring new players into a false sense of security before Halicarnassus painfully demonstrates what a DifficultySpike is. Whereas the preceding bosses took some time to get going, Hali takes all of a few seconds to start the fight with a devastating CriticalHit tank buster[[note]] which [[ExactlyWhatItSaysOnTheTin always crits]] if the tank isn't using the role skill that negates it, doing a whopping 72k damage before mitigation or vulnerability[[/note]] immediately followed by [[ThatOneAttack Spellblade Holy]].[[note]] which in Savage places several [=AOE=] markers and one stack marker on players and then ''stuns them and swaps their positions'' before the [=AOEs=] land, instantly wiping the raid if players are positioned wrong[[/note]] The fight only gets worse from there with her multiple "game board" arenas and her Queen's Waltz attack which changes its properties depending on the current board, culminating in a final phases with tiles from ''all'' the boards and her jumping around them to determine the Waltz's effect.
* [[spoiler:The false Inquisitor Guilleman]] is this primarily because the fight is essentially an EscortMission. The boss himself is pretty standard, but your AI companions ''have'' to survive, and their AI is basically braindead and will get chumped easily unless you take out the boss's adds pronto. Depending on your gear, you may very well need the Echo Enhancement buff to win, and even then its not a given.
** The Level 70 Scholar job quest is this UpToEleven. It's set up like a dungeon boss fight, except you only have one tank and one DPS with you as the healer. This shouldn't be too bad, as the [=NPCs=] can take a fair bit more damage than a player at their level, the boss doesn't hit as hard as a true boss at that level, and you're a healer. The problem is that you and your [=NPC=] allies aren't partied. Because of this you're forced to directly click on the NPC you want to heal instead of selecting their health bars, and the tank is a ''Lalafell.'' Next to the Elezen lancer and the extremely large boss he can be frustratingly hard to target when he needs healing. Also because they're not in your party your fairy, who is a large portion of your healing, won't heal them. Further the boss and its adds have several attacks that are [[GangUpOnTheHuman specifically scripted to target you]] so you have to keep up the healing while dodging multiple [=AoE=] attacks, some of which are exceptionally large. You also don't get the Echo Enhancement if you fail since it's a job quest and not a main story quest.
* The Rabanastre 24-man raid has a couple that often frustrate players:
** Mateus, the first boss, requires the teams to play out their parts in different portions of each phase. A lot of people coming into the raid are used to simply mowing down the boss and only occasionally going back to their markers to do something. This fight requires that each party do something at different points, otherwise it makes continuing the fight practically impossible. The second phase has a gimmick where everyone gets a debuff that stacks over time, with 9 stacks resulting in death. To reset it, players need to kill adds. Players here either forget to reset the stack or not focus on the adds. The third phase also requires each party to coordinate in order to not induce an ''alliance'' wipe.
** Hashmal, the second boss, is considered to be the most difficult boss of the entire raid. Many of his attacks can cleave and will probably instantly kill anyone that is not a tank. Hashmal will also charge up an attack that will have one of his arms light on fire and if you are not on the opposite side, his attack will either instantly kill you or do heavy damage and give you a heavily damaging Burns debuff that will kill you after one or two ticks. Hashmal will also summon two pillars that he will cut down and will instantly kill anyone that gets squashed by them. Following that, the boss will bring up a command tower that must be destroyed quickly or his ultimate attack will kill everyone instantly. Not only is this sequence a DPS check, Sand Spheres will also appear as a second DPS check where they will cause heavy damage to the entire alliance if they're not destroyed in time. If more than one Sand Sphere goes off, it's probably an instant wipe. Complicating matters further, Hashmal will also summon two golems that will spam hard hitting AOE attacks that will only grow stronger every time, so the alliance needs to burn them down quickly before everyone dies. It's not unheard of for alliances to use their limit breaks on the golems just to prevent any more damage going out. Uncoordinated parties generally fail here.
** Construct 7 in the Ridorana Lighthouse raid is considered to be tough for two reasons. One, it has an attack that shoots [[EnergyWeapon Frickin' Laser Beams]] in a circular motion which will kill you if you don't outrun it plus the boss uses it for a longer duration in the second part of the fight. Two, the boss has a lot of [=AOEs=] as well as attacks that will target random players that will also hurt others standing near them. Three, it will use a gimmick where it reduces everyone's HP to single or double digits and then require you to stand in a circle (marked with one, two, three, and four dots) that boosts your HP by a certain number while doing ''multiplication math problems'', such as requiring your HP to be in multiples of four. Botching it will have the boss's follow up attack either hurt a lot or just outright kill you. In the later portions of the fight, not only does the boss bring back the multiplication gimmick, you also have to use prime numbers!

* The Phantom Train in Sigmascape V1.0 (Savage) is noted for being a morale draining fight. Much of it has to do with a complex string of mechanics that's RNG heavy, often leaving no room for error. Two of them suck away a player for a non-trivial amount of time. At least for a player death they can get back in the fight within seconds, screwing up the one mechanic that gets players whisked away means they're out of the fight for at least a minute which is a huge DPS loss. And the DPS requirements for the boss are ''very'' tight, so you can afford very few screw ups.
* An interesting problem that mainly just applies to unsynced Extreme bosses is bosses that wipe you when you do too much damage too fast. Certain bosses have mechanics that wipe you if you do not complete them in time, which is pretty standard. But, if you do enough damage to move said bosses to the next phase, they will consider said mechanics not completed before time ran out and will wipe the party. Even with everyone's much higher health and defense stats, these attacks will still wipe. Therefore you cannot simply just DPS as hard as you can, you have to know every health threshold the boss has so you can DPS up to it, complete whatever mechanic is required, then continue. Ifrit EX is the first boss to do this. If you ignore the nails and simply wail on him, he will consider the nail mechanic failed after losing enough health and wipe the party, even if you have enough DPS on the final set of nails to kill him before time runs out. These bosses can make grinding for mounts/gear for glamours a real pain in the ass.

* The Thunder God in the Orbonne Monastery has a sheer number of mechanics that can catch many first time players off guard. He starts the fight with Cleansing Strike, which brings the entire alliance down to [[HPToOne just 1 HP]] and inflicts Doom, which will kill everyone in 10 seconds unless they are healed back to max HP. The boss also auto attacks all of the tanks at once constantly, so healers from every alliance have to keep on top of healing their tanks. The Thunder God will then use several attacks which requires players to be positioned in certain ways; he can either attack the outermost portion of the arena, the innermost portion of the arena, attack one whole section (circular areas) of the arena, or attack whole sections one by one. Next up, his Crush Weapon attack will mark someone and they have to constantly run away as the attack will follow them and hit multiple times, which will kill the player in 2 or 3 hits if they can't avoid it. Crush Helm has all the tanks suffer Magic Vulnerability Up, which makes the next attack very likely to kill them unless the tanks have their defensive moves popped up and/or the healer removes the debuff in time. Another attack the boss has needs everyone to stand in a circle (3 per circle) to minimize damage from his next attack, which will get a damage increases if there are not enough people standing in the circles. Another attack he'll use involves a mechanic similar to Ozma where the boss will drop an AOE circle on a player and if the circles touch each other, the entire alliance will get hit for big damage and a bleeding debuff. He has a tether attack that contrary to what might seem logical cannot be grabbed by the tank. It is a multi-hitting attack that applies a defense down buff, and one to two stacks of it will cause the tank to be melted by the boss's auto attacks. It has to be passed between the DPS and healers between each strike to be successfully handled. Lastly, the boss will use Crush Accessory where the entire platform is covered in damaging ice and each alliance then has to kill the Icewolves that appear or they'll explode for massive alliance-wide damage. Needless to say, the Thunder God quickly grew notorious for being a PUG killer.
* The normal version of Omega has served as a rather difficult challenge for the average player. It has many hard hitting attacks and requires a fair amount of area awareness. But it's most infamous move is the Wave Cannon, a laser attack that covers about 200 degrees of the area around Omega on either it's right or left side. And the only way to know which side is getting blasted is whether it casts "Starboard Wavecannon" or "Larboard Wavecannon". Even ignoring that "Larboard" isn't used anymore in favor of "Port", if you aren't familiar with your nautical directions, you are in for a ''world'' of hurt, as the attack markers on the ground only appear for a split second before damage goes out, mostly to let you know whether you succeeded or failed the mechanic before it goes out. And the worst part is the attack flips the boss 180 degrees before it casts the attack again in a random direction, so you have to be able to figure out where the boss's right or left is twice in quick succession.
* While technically it might qualify as a FinalBoss, 4.56 brings us [[spoiler: the resurrection of Zenos yae Galvus, via Ascian]], which involves a very lengthy (if simple) fight where the player takes control of Hien until the Warrior of Light can do their BigDamnHeroes thing. From there, the fight requires a ''hard'' DPS check which is nearly impossible for a lot of classes, a check which outpaces even the aforementioned Sadu fight. And if the player fails the DPS check, they have to do the Hien part ''all over again.'' Thankfully, these days it's a simple task to get gear which makes the check trivial, but upon release it required a lot of grinding or an answered prayer to even have a chance.

* The Red Chocobo is the absolute bane of the Bozjan Southern Front. Every one of its attacks is a potential OneHitKill, and the [=AOEs=] of its attacks are ''everywhere'', giving very little room to dodge without getting blasted to the Seven Hells and back. Players who know how to fight it still fear it, and anyone going into it blind is likely going to die repeatedly. Using Reflect can protect you from most of its attacks, but you'll still gain stacks of Vulnerability Up every time you are hit, making you into a GlassCannon if you get hit when you're not under Reflect.

* The Red Chocobo is the absolute bane of the Bozjan Southern Front. Every one of its attacks is a potential OneHitKill, and the [=AOEs=] of its attacks are ''everywhere'', giving very little room to dodge without getting blasted to the Seven Hells and back. Players who know how to fight it still fear it, and anyone going into it blind is likely going to die repeatedly.

* Speaking of Alexander Prime, the last boss of the Alexander raid series is notable in that you ''need'' to use a Level 3 tank limit break to survive its Ultimate on the ''normal'' difficulty. And it needs to be timed just right, otherwise the effect will wear off and you'll have a party wipe anyway. There's also the "Timegate" mechanic that puts players into a 1v1 scenario with a {{Mook}}; if even one of those players dies, it's probably a wipe. The Savage version manages to catch up with Savage Cruise Chaser's difficulty based on his sheer damage output on top of all this: everything that isn't Alexander Prime's auto-attack will do between 20k and ''50k'' damage unmitigated, several of these are tank busters that are '''used in combos with each other''', and ''all'' of said tank busters are cleaves[[labelnote:*]]the attack will hit multiple party members if it is pointed at them[[/labelnote]].

* For the hardcore raiders, Halicarnassus in Deltascape V3.0 (Savage). Alte Roite and Catastrophe were hard-hitting but ultimately easy-to-learn bosses that didn't have too much HP, luring new players into a false sense of security before Halicarnassus painfully demonstrates what a DifficultySpike is. Whereas the preceding bosses took some time to get going, Hali takes all of a few seconds to start the fight with a devastating CriticalHit tank buster[[labelnote:*]] which [[ExactlyWhatItSaysOnTheTin always crits]] if the tank isn't using the role skill that negates it, doing a whopping 72k damage before mitigation or vulnerability[[/labelnote]] immediately followed by [[ThatOneAttack Spellblade Holy]].[[labelnote:*]] which in Savage places several [=AOE=] markers and one stack marker on players and then ''stuns them and swaps their positions'' before the [=AOEs=] land, instantly wiping the raid if players are positioned wrong[[/labelnote]] The fight only gets worse from there with her multiple "game board" arenas and her Queen's Waltz attack which changes its properties depending on the current board, culminating in a final phases with tiles from ''all'' the boards and her jumping around them to determine the Waltz's effect.

* An interesting problem that mainly just applies to unsynced Extreme bosses is bosses that wipe you when you do too much damage too fast. To clarify, certain bosses have mechanics that wipe you if you do not complete them in time, which is pretty standard. But, if you do enough damage to move said bosses to the next phase, they will consider said mechanics not completed before time ran out and will wipe the party. Even with everyone's much higher health and defense stats, these attacks will still wipe. Therefore you cannot simply just DPS as hard as you can, you have to know every health threshold the boss has so you can dps up to it, complete whatever mechanic is required, then continue. Ifrit EX is the first boss to do this. If you ignore the nails and simply wail on him, he will consider the nail mechanic failed after losing enough health and wipe the party, even if you have enough DPS on the final set of nails to kill him before time runs out. These bosses can make grinding for mounts/gear for glamours a real pain in the ass.

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