Make no mistake, Darkest Dungeon is not a case of Hard Levels, Easy Bosses. Your heroes are just as likely to die to these guys as much as anything else. Especially when some of them can appear without warning.
- Most of the bosses only require you bring your best team and get decent luck. If you go in blind, the Hag will annihilate your best team, in horrible circumstances. She is identified again and again as the most frustrating enemy in the entire game.
The Hag takes up row three and four in her "formation", with her pot in rank one and two. What this means is, most of your reliable heavy hitters won't be able to touch her, only the pot. She immediately puts one of your heroes in the pot meaning that even if you did bring a hero that can reliably do damage to her, she might randomly completely disable them and quickly strip them of their HP. Even if you overturn the pot, it immediately respawns and she will put another hero in at the next round. To top all this off, she gets multiple turns every round to cause damage and stress to the rest of your party, and if you retreat with somebody still in the pot, you've just abandoned that poor soul to getting boiled alive and eaten. Good luck! The game is also cool with this combo: Hero falls from pot, she death blows them and immediately puts a new hero in.
- The Siren can be this if you bring a high damage output character like a Leper or an Abomination. If she takes them with her Song of Desire move, get ready for a world of hurt from your own units. Even worse if she takes a Flagellant, as she can heal herself tremendously if he uses his Redeem move or is put on Death's Door. Oh, and she also occasionally spawns a Cove enemy (and is much more likely to do so if she fails to mind-control a hero). Yay.
- Brigand Vvulf stands out from most of the other examples as he's the boss of his own mission. It's a Short one, so you cannot use camp buffs to aid you during the fight, and the lead-up to his room involves several encounters with tough brigands that force your party's Stress to skyrocket. Once you actually get to him, he's got a sizeable health pool and constantly lobs bombs at your party to do massive damage while calling in other brigands to harass the party. You can opt to destroy the Barrel of Bombs to defuse the bomb, but every strike on it causes a damaging retaliation. To top it all off, Vvulf's mission appears randomly after you have a few Heroes at the highest Resolve Levels, and if you don't get a party together to face him rightaway, he'll destroy some of your town upgrades.
- The Brigand Cannon also proves to be a formidable foe due to being a Flunky Boss with a rather large health pool, a sizeable PROT, as well as being immune to any debuff, as it is literally Made of Iron. Throughout the battle, one of the units it spawns in is a fuse man. This requires you to shift your attacks from the cannon to this fuse man, or else you will be shot by the cannon itself, which predictably does a huge amount of damage to each of your characters and also stresses them out. This is a nasty combo when it spawns a Brigand Cutthroat, who can bleed one (or unluckily, two) of your heroes, which makes it very likely for them to die if they're not healed. However, the cannon will occasionally misfire and stress heal your party in the process, but it happens rarely enough that you don't want to rely on that happening.
- The Swine King would be relatively simple enough if he was just a straightforward tanky boss. That isn't the case here, as he brings his spotter Wilbur with him. Wilbur is a capable fighter on his own when not just marking targets for the King to hit. His Squeal attack does chip damage, if at all, and has a good chance to stun its target (read: your entire party). This attack is so surprisingly effective that he can pick off heroes brought to Death's Door with ease, so much so that it's lampshaded by having its own achievement. With how much the game follows the Shoot the Mage First formula, you'd think that killing Wilbur would be the easy solution, right? Think again. Attacking Wilbur will make the Swine King hit the whole party instead, and if you happen to kill Wilbur, the Swine King will go ballistic and start hitting your whole party with powerful attacks. Unless you're prepared, on the verge of victory already, or ridiculously lucky, this will end in a party wipe within a few turns. The only saving grace is that, in a rare moment of Anti-Frustration Features from this game, a hero will warn you that nothing good will come out of attacking Wilbur first.
- The Collector is a rare Bonus Boss that has a low percentage of appearing in any dungeon (which goes up the more items are in your inventory), but ill-prepared players will be wary if it decides to show its face due to its unpredictable appearances. Sporting a decent amount of health, it calls upon its collected heads to deal high damage and to buff/heal one another. Those heads always spawn in front of it, shunting the Collector all the way to the back ranks, out of reach of your melee attackers and forcing you to fight through those heads again and again. In reality, Collector is relatively easy to deal with compared to some of the primary bosses, with combination of debuffs, stuns and ranged attacks being more than enough to take care of him in 3-4 turns - but considering his random chance of appearance, he often ends up being the first boss that actually requires putting that playstyle to use, severely punishing players that overrely on melee characters and brute-force though battles.
- The Shambler. It will only arrive if you either are traveling at 0 torchlight or activating a particular curio, so, thankfully, you have some measure of control over whether or not you have to fight him. That's where the good news ends. The shoggoth Expy is notorious for automatically reducing your torchlight to 0, always ambushing the party, shuffling your heroes around (hope you like having your leper stuck in the back and your occultist up in the front), inflicting party-wide bleed, blight, and shuffling, and spawning in tentacles every turn that, though weak at first, get massive buffs every time they attack you. It is well-known among the community for being perhaps the hardest enemy in the game, bosses included. If you have sad memories of accidentally bumping into one and losing a favorite hero, you're not alone. Also, things like difficulty settings have zero effect on how often it can appear as a random encounter in the dark, meaning that you can encounter it as early as the second mission in the Ruins on a Radiant run if you're daring, or stupid, enough to go in with the torchlight gone, essentially making it a complete party kill of your low-level heroes during the encounter.
- Just like the Collector, the Fanatic has already gained a vicious reputation for showing up to ruin runs. However, instead of flunky heads that keep buffing, protecting, and stabbing, he just brings an endless stream of pain thanks to the fact he's a hard-hitter and gets three moves per turn, not to mention removes a character to burn them at the pyre and subjects you to a sadistic choice due to the fact that cutting down the stake buffs him and destroying it entirely pisses him off and makes him start doing Fury of the Righteous, dealing serious physical and stress damage to your entire party. Oh, and if you run away, he will chase you down and show up right on the next encounter. Thus, if you don't beat him, your only options are giving up on the mission altogether (which hurts even more because anyone abandoned at the pyre dies if you flee, similar to what happens to anyone in the Hag's pot) or losing everyone in your party. Even worse, when you encounter him, he auto-surprises your team, and his first act is usually to throw a hero up on the pyre, so you pretty much bet a heros life as soon as you dont quit the dungeon upon seeing his face on the load screen. Oh, and the game is totally cool with the following scenario playing out: hero falls from pyre at deaths door, and gets released just in time for the Fanatics turn. The Fanatic immediately death blows the hero, and binds a 2nd hero to the pyre. Make NO mistake, just by encountering him, youre almost guaranteed to lose at least one hero.
- The Crocodilian is essentially the developers' way of giving the player the middle finger. It's a Mini Boss in Mook Clothing with ridiculously high stats, shielded by three river plants that inexplicably have the health, dodge, and protection of an Army tank, and is capable of dealing tons of damage and stress damage to your poor adventurers. But the worst part is that it appears in what's supposed to be a level one mission, and you won't know it's there until you find it. One of the few things that work are heavy bleeds, as the Crocodilian has multiple actions per round and very low resistance. Updates post-launch made its Submerge skill cure it from bleed and blight, but reduced its overall health so upfront damage is more viable. Interestingly, it doesn't transmit the Crimson Curse.
- The Baron isn't quite as bad as the Crocodilian, although since you need to fight two of them at various points in his multi-stage super-dungeon, he can probably score a few aggravation points off them as well. In theory, this tick-shaped bastard is a straightforward Damage-Sponge Boss; he has a lot of HP, but comparatively low damage. However, that comparatively low damage can come out three times in a round and brings with it options like The Thirst (which heals 18 HP on a successful hit), Crowd Pleaser (minor damage to all of your party members), and, worst of all, Necessary Discipline. This move can throw your formation into chaos, and inflicts stress, bleed, and horror on the unfortunate character hit with it and given the number of actions he has in a turn, if he targets a slow character, they can have multiple applications of both before actually getting to take a turn and use items to remove them. Finally, at various stages in his fight, he summons flunkies but instead of just having them turn up, he creates a selection of pods, hides himself in one and minions of various power levels in the others, and shuffles them. Now, while any of these pods is intact, you can't use any move that would heal a party member. This includes moves that have other effects and simply heal as a byproduct, meaning that your Vestal loses her Judgement ability and your Abomination can't change back if he's in beast form. And if you don't pop all the pods fast enough, the Baron will open all remaining ones after a couple of turns, which is a situation you very much do not want to be in, especially at the third tier (when powerful Bloodsuckers like Esquires start turning up).
- With new DLC comes new bosses hard enough that you could use them for horseshoes. Let's talk about the Miller. Two actions per round, high resistances and a lot of HP with minor protection, sounds relatively manageable. Summons minions constantly, okay. Admittedly, some of those minions start out stealthed, and others he turns into very durable shells that deny you the ability to guard and hit your people with Horror debuffs, but they're just minions. And sure, he has a life-steal attack, but he doesn't use it often and it does ameliorate your stress a little bit. Then he starts Reaping. This move is That One Attack by virtue of being a fairly accurate, high-damage, high-crit attack that targets everyone in your party, and the AI does not have anything to prevent it using it multiple times in a round. There is a trinket you can get that makes the bearer immune to it, but between the multi-targeting and the inability to guard you probably have at this point, expect to take a lot of punishment even if you win. On the bright side, when you fight him in Endless, beating him takes you to a rest area and means that you've reached stage two of the mode, so even if you run (which isn't necessarily a bad idea if you look like most parties do after fighting the Miller) you at least get a sack of cash for it, and death isn't permanent in Endless Mode, so the casualties will return in a couple of weeks.
- The Color of Madness also brings us the Thing from the Stars. Again, it looks manageable at first, with no protection and only moderately high HP - until you reduce it to half health, at which point it Turns Red and gains a protection buff so strong that your regular attacks won't do anything more than Scratch Damage. What's that? You think you can bypass the protection with Blight? Nope: it erases debuffs and DOTs every turn, meaning it's impossible to stack them. Oh, and all the while it's dishing out massive damage/stress to your entire party and summoning Action Bombs every round. The only saving grace is that the game tells you which dungeon it's lurking in each week, so you can avoid it if you're not prepared to face it.