History ThatOneBoss / LimbusCompany

[[folder:Main Story]]
* Being the FinalBoss of Chapter 3, Kromer is appropriately pain-inducing to beat. Right off the bat, her first phase ''has no damage weaknesses'' and in particular resists Blunt, which can be a nasty shock since most of the enemies in the chapter and dungeon are ''weak'' to Blunt instead. Then, she has a passive that gives her a huge heal and attack buff if she has any Bleed or Burn on her at the end of the turn, which can NoSell an entire turn's worth of effort and renders the Kurokumo, Liu, and N Corp. Identities useless. GameplayAndStoryIntegration also bites you hard if you bring Sinclair along and don't have a full collection of the dungeon's specific E.G.O gifts, as he will take a huge performance debuff without them. Clashes against Kromer, if lost, will have her do disturbing amounts of damage and[=/=]or nail stacking that can stagger a squishier Sinner in a single combo. Furthermore, at regular intervals, she'll use an attack that instantly Staggers the targeted Sinner and makes them take ''double damage'' the next turn ''on use'', after which she'll fire all of her attacks at them (several of which are her 4-coin Purification attack) and force you to redirect every attack to avoid their almost-certain death. The only consolations are that you can deal some serious damage if you win the clash against her "I Shall Claim Your Life!" skill in the first phase to instantly stagger her, she'll start taking and dealing double damage past a certain point in the fight to let you bring the hurt, and if you manage to reach her second phase with your team relatively intact, the fight becomes far easier; while she can still bring the hurt with some powerful attacks, she actually has weaknesses to Wrath and Pride affinities as well as a Fatal Pierce weakness on her Maw part, will periodically drop her defenses further when going on the attack, and and can similarly be forced to Stagger if you win a check event after dropping her health enough, making her ''much'' squishier.
** She, too, was hit with the {{Nerf}} bat at the start of April 2023. Now, by collecting the "A Sign" items in the dungeon, you can reduce Kromer's regen and power gain all the way down to zero. There was a glitch that made it so it didn't work in the second phase, but that's since been fixed, making her ''much'' more manageable for anyone running the aforementioned groups of Identities.

* The ClimaxBoss of the second part of Canto VI, [[spoiler: Mirror Heathcliff]] is effectively a dungeon boss that has to be fought during normal story progression. This actually causes ''significantly'' more problems than you'd think, as [[spoiler: Heathcliff]] has a massive HP pool, high rolls, resistance to all three damage types and unique mechanics, while your Sinners start the fight with 0 Sanity and no E.G.O. resources or any other kind of collectibles that help you. The boss itself starts with 15 Sanity, and as a result the first few turns effectively boil down to a LuckBasedMission because they can easily snowball over your Sinners in terms of Sanity due to gaining a big chunk of it every time they win a clash, and having their conditions to lose SP being much more hard to accomplish. [[spoiler: This is complicated even more by Mirror!Heathcliff's gimmick; he only targets the original Heathcliff and wins the fight if he dies. If you're particularly unlucky with speed die rolls, the fight can end in an instant because Mirror!Heathcliff will outspeed your team and blitz Sinner!Heathcliff down, something particularly troublesome later in the fight when he starts using attacks that can ''only'' be clashed by Sinner!Heathcliff. If your Heathcliff gets staggered or Corrodes even once, the fight is practically over because those attacks become completely unavoidable, and they ''will'' inflict so much Bleed that even if he survives the initial hit he'll be dead next turn. While Bind and Haste support can help with keeping Mirror!Heathcliff slow enough to redirect his attacks, this is not something that can realistically be fueled every single turn, and even then that does not defang his brutally high damage that can easily cut down your defenses.]] It's practically [[CharacterSelectForcing required]] that you bring massive amounts of Sinking and beefy Identities that are of a relative speed (which are far and few between) to redirect at least some of the attacks and pray you get good flips on the first few turns so you can keep [[spoiler: Heathcliff]] on as little Sanity as possible and have some chance to actually build up resources. And even then, one bad turn can end the fight immediately.

* With My Form Empties being hit with the {{Nerf}} bat, Dream-Devouring Siltcurrent quickly rose up to take its place as what is likely the toughest FinalBoss in the Hard Mode of Mirror of the Lake. It packs a boatload of health and innately powerful rolls boosted further by the accumulated enemy buffs on Floor 5, and will inflict 1 Paralyze to all Sinners at the start of each turn until you break its Fluorescence; E.G.O. is already practically mandatory to outroll its boosted clashes, but now not only are all plus-coin clashes crippled in general, E.G.O. will always roll tails and most likely lose unless it uses negative coins, upon which Siltcurrent will almost certainly stagger or kill the target with its extremely powerful moves. Fortunately, the fight gets easier if you can repeatedly break its Flotsams to redirect its Blind Obsession attack, but since there'll always be at least one turn where no Flotsam is present, someone will have to either gamble on outrolling it with a Paralyzed E.G.O. or sacrifice a major chunk of HP to take the hit, if not their life, not to mention the player also having to deal with Siltcurrent's other attacks while making sure one Flotsam is destroyed per turn. On top of that, Dream-Devouring Siltcurrent will always use an unclashable [=AoE=] attack that hits the whole party on the first turn, which normally does very little besides setting up its unique battlefield hazard, but with the Mirror Dungeon buffs now becomes a legitimate burst of cheap damage that can leave Sinners staggered and helpless on the next turn.

'''NOTE:''' As they are [[{{Superboss}} intentionally designed to be extremely difficult]], the final bosses of the Refraction Railway cannot qualify.