Hard bosses exist. Annoying bosses, however, are another can of worms that can maybe ruin a player's day even more.
- You Want To Get Beat? Hurtily? is easily considered the most annoying Thread Luxcavation boss for the simple fact you just cannot speed it up if you fight it manually due to their resurrection gimmick, meaning you have to empty out their health bars multiple times, go through a rather annoying choice prompt three times, and only then get the chance to kill it. It's not hard, just time-wasting. Fortunately, there is the option to skip the fight for the rewards, but not within the Mirror Dungeon.
- The Blubbering Toad in Line 1 of the Refraction Railway has very low damage output and relatively nonthreatening clashes, but has a tremendous amount of health, low stagger thresholds, and significant resistances to all types of physical damage (its weakest physical resistance being its eyes being only Normal to Pierce), making it hard to take out quickly if you don't have a high-power Pierce identity to pop the eyes and expose a Fatal weak point, or massive amounts of Damage Over Time. Its constant unavoidable SP drain also heavily cripples your Sinners by making them unable to roll heads to deal major damage or beat the Toad in clashes (which will result in even more SP loss), lose turns panicking, or be unable to use more powerful E.G.O. at the risk of Corroding and turning on their allies.
- To go alongside its minions, Papa Bongy is an incredibly annoying boss to fight. His main gimmick revolves around his ability to be a Flunky Boss, dealing SP damage based on how many Bongys are on the field at the time. Adding to it is his Chicken Bucket, which can constantly summon more Bongys unless it's broken. He's more a frustrating fight rather than hard, as it only takes one coin flip going wrong to go from a full healthy party to being put in a corner - especially considering most of its skills have a lot of coins, so you better bring a good clasher like Seven Outis to get them removed reliably. Also not helped is the hard fight is the most efficient way of grinding the event ladder, especially if you use the bonus units, who aren't particularly designed to capitalize on the boss's weakness, leaving the player to be on a Catch-22 of having a harder time or having to grind more.
- In Line 2 of the Refraction Railway, several of the bosses seem designed to less actively threaten the player, and more just stall for time and inflate the turn count. One of the worst things about said bosses is that they tend to debut in earlier Cycles, which means that you have to confront them multiple times:
- Steam Transport Machine alternates between offensive and defensive stances depending on the turn count, can heal itself, and notably becomes ineffective to all damage types and affinities starting from after you destroy the body, at which point the core will still likely have a lot of health left unless you heavily overdamaged the body last turn. If you didn't pour all your DPS into the boss during the turn when you staggered or broke the body, you're going to be in for an extremely painful slog of a fight after.
- Drifting Fox gains a special buff that gives it Protection scaling with the number of cycles you've gone through. At four cycles or higher, this effectively translates to the Fox taking 60% less damage at all times along with its beefy health pool, and without Fragile stacking, you can only get rid of the Protection for a maximum of one turn (after killing its Umbrellas) before it just gets it back again. Not to mention that killing all the umbrellas to dispel the Protection gets more painful at higher cycles as their number also scales with cycle count, and unlike the regular fight, using AoE skills is out of the question since Drifting Fox will gain an Attack Reflector during the summoning phase.
- Faelantern's gimmick is that in its Fairy phase, it will charm a number of your slowest Sinners scaling with the cycle count and how long the fight has gone on for, making them helpless while launching unclashable attacks that also heal the main body. At higher cycle counts, this translates to only having 2 or 3 random Sinners available at the start depending on your luck with speed rolls, and you're in for a world of hurt if the few Sinners you have left don't have enough damage output to break its Fairy part before it fires one too many attacks, and whether those Sinners even have the right damage types is almost up to luck. Even if you break the Fairy to expose the body, you have only one turn to attack its body (two if you can stagger it) before it just goes underground and repeats the process, but with more charmed Sinners and more health. On top of that, it can't even be cheesed in the Fairy phase due to damage to the Fairy not carrying over to the Core, and the core also purging all debuffs whenever it goes back underground.
- Shock Centipede had its fight reworked for the Railway, in the process making it far more painful. All its attacks now grant Self-Charge on combat start (instead of on use) but only lose it on clash lose, making it deceptively hard to keep track of how much charge it has, and even harder to stop it from building up charge. It's even worse if you bring it to 1 HP or break a part to cancel its actions, since now that you can't clash with the canceled attacks anymore, it'll freely generate Self-Charge with no way to stop it. This translates into it being very difficult to stop or weaken its Last Stand mode at 1 HP, upon which it will proceed to stall you out for 2 or 3 extra turns before finally kicking the bucket. Charge teams are also in for a nasty surprise, as it can now drain your Charge on hit and turn it into more Self-Charge. The only way to actually drain its charge is by countering its mass attack or cracking its shield in its coiled phases, both of which occur at fixed intervals to mess with those trying to optimize their turn count.
- Ambling Pearl is the second boss of Canto V's dungeon, and isn't exactly a hard fight once you understand the gimmick. It starts with 10 Green Slime, which it loses a stack of every time it attacks, and spawns a slime enemy in one of three spots every time it loses a stack. If it hits 0 stacks, it'll automatically stagger, which is the only way to meaningfully damage it due to it being a Stone Wall otherwise. After its first turn, it'll start using a high power Predation attack on the slimes, gaining more Green Slime stacks if it hits, starting by targeting one slime and then three on the next turn. The goal is to kill the slimes before the boss can, as after three turns it'll use a mass attack that sets it right back to 10 Green Slime... which is where the problem lies. Ambling Pearl itself is still attacking the whole time, usually leaving only one or two Sinners free to deal with the slimes before the boss can eat them. If you fail to kill a slime before the boss can, due to low rolls or bad attacks? Well then you have to start the whole cycle all over again, because the boss won't be out of Green Slime before it can set itself back to 10 stacks and render all your efforts on that cycle pointless. Oh, and with the slimes themselves passively poisoning everyone every turn, one unsuccessful cycle can easily result in a Disaster Dominoes of staggers that can make the fight unwinnable due to not having enough attacks to both clash with Ambling Pearl and kill the slimes on time.
