That One Boss / Trails Series

These bosses have definitely made life difficult for the Trails Series fans.

The Legend of Heroes: Trails in the Sky

• From Second Chapter:
  • The Prologue boss, Kurt, is durable, capable of healing himself, and has crafts that can knock party members across the battlefield to make it long and tiring to find opportunities to kill him. On Normal he's more of a Goddamned Boss, but on anything higher this fight is a brutal roadblock for many players, as the boss' damage output is far more than you can reasonably heal off at this point in the game, and he can easily run you out of EP. And the Blown Across the Room effect on his basic attacks hurts Anelace's usefulness a lot, since she has no long-ranged Crafts. He's also very fast, and can often get multiple turns in a row to kill your characters before you can heal.
  • Captain Amalthea's tank at the end of Chapter 3. Its HP and defense are stupidly high for this point in the game, and it's only the second fight of three consecutive boss battles. (The third one, fortunately, is easier, but the tank is practically a Marathon Boss on its own. And it doesn't exactly slouch in attack power either.)
  • Luciola. She has powerful Fire attacks that hit several of your party members and is flanked by multiple minions with high evasion and the ability to cancel arts and inflict Sleep, AND two bulky minibosses that are immune to arts and physical attacks respectively. The second fight with her is particularly bad as she has TWO devastating S-Crafts to demolish you with AND can summon clones that cause you to hurt your party members when you attack them, meaning if you've been relying entirely on Area-of-Effect attacks until now, you're in for some serious pain.
  • Regardless of the difficult level, both fights against Renne, the "Angel of Slaughter", are tough because her S-Craft can One-Hit Kill the entire party (before you even get a turn) if you haven't equipped everyone with deathblow-preventing acessories. To make things worse she don't fight alone: in the first battle, she has some Gorgons, who love to shot petrifying lasers from afar; for the second battle, she fights alongside Pater Mater, who possess a mountain of HP and can punt you across the arena and revive Renne if you go kill her first.
  • Justified with Loewe, whose fighting prowess is often commented on by others. He is such a formidable foe that the game actually lets you choose to proceed without defeating him. Loewe will create doppelgangers (which, unlike previous Enforcers, are not illusions but full-fledged new enemies to deal with), interrupt your casts (and his doppelgangers share this ability), is flanked by two tenacious mini-bosses that can heal him and will frequently open the fight with his S-Craft, Dead Emperor Sword, which will most certainly hit all your team members (or only 3 of them if they are spaced out) and possibly kill them outright, or leave them at death's doorstep at best. In short, you will begin the fight severely wounded (unless you bring Kevin with you and use his S-Craft, Grail Sphere, right off the bat), and chances are Loewe will finish you off quickly if you don't heal your party to full health immediately. And if you manage to survive the first turns, then you will be outnumbered once the doppelgangers join the fray. The saving grace is that Loewe and the mini-bosses (but not the doppelgangers) aren't immune to Clock Down, allowing you some breathing room once you manage to stick the status debuff on them. For all these reasons, Loewe is considered to be the hardest boss of the game, even harder than the actual final boss.
• From the 3rd:
  • Grimoire!Kevin and his five Death Sluggers from The Third. For starters, he likes to spam Grail Sphere EVERY TURN. And the sluggers...OHMAIGAWD THE SLUGGERS. They have an attack that hits one ally unit multiple times with high damage each depending on the difficulty, with four times in nightmare mode. This boss fight is basically a race on who can inflict high damage the fastest and unless you bring Kloe for her +50% Def S-Craft bonus, you won't survive.
  • The spider boss in Chapter 5 of The Third might qualify too. Let's say that you hurt its children too much.
  • In The 3rd, Cassius is often compared to Loewe and while he has slightly lower stats than Schwarzritter on paper, he makes up for it with his cheap craft selection. His Lightning Flash craft has an AOE to rival S-Crafts and higher end arts, his Rend Armor craft is a fairly wide line AOE that AT Delays, his S-Craft hits the entire field, and he can buff his STR and SPD to make the previous points worse. He's also completely immune to debuffs and all ailments, ensuring that the player can't do anything to weaken him like with previous bosses. The only saving grace is that he has no minions and doesn't seem to inflict many ailments.
  • In The 3rd Schwarzritter aka Loewe isn't quite as tough as when he was a boss in SC due to summoning clones later in the fight and only having one robot minion, but like Cassius, he has complete immunity to both ailments and debuffs.
  • The first three bosses of the Boss Rush in The 3rd always start the battle as an ambush encounter, meaning they and their mooks get the first turn. If you don't have enough CP to S-Craft most or all of the mooks before they can move, you'll probably have to restart most or all of the final chapter. The worst of them is R-II Gespenst, which has Delay Cannon to AT Delay party members that are bunched close together. In contrast, the fourth boss aka the Final Boss gives you the first turn and more than enough time to set up buffs.

The Legend of Heroes: Trails from Zero and Trails to Azure

• Of the optional high-level monster chests in Zero, the two Armored Hydras on Mainz Mountain Path are another level of brutal. They take at least half your HP with any attack, and are incredibly durable, but it's their Crafts that are the real problem. Petrify Breath is an area petrify attack and virtually death to anyone not immune, Earth Shaker hits the entire party for massive damage, and Grand Flash is a full-field Delay in a game with no Delay immunity, all you can do is pray it misses your most vital members. (Usually Elie or Tio) If you're unlucky with Grand Flash, you might never get a turn.
• The sidequest battle with Bracers Lynn and Aeolia is surprisingly brutal for two characters you've never seen fight before. You first have to take them on with just Lloyd and one teammate of choice, where they thankfully hold back. Second round, they let you use the whole party, and you'll need it. Lynn is a Taito student and carries several of Zin's Crafts from the Sky arc, including the double Strength/Defense buff Distend, except she gets to act again after using it, and she also packs a line AoE attack with a chance of instant death. Aeolia is arguably even worse, being immune to all ailments and debuffs, using General Anesthetic to inflict Sleep and Seal all around her, Local Anesthetic for severe debuffs and Toxic Knife to hit in a line for random ailments including instant death. She can also heal herself and revive Lynn if she goes down. This wouldn't be so bad if it weren't for how insanely fast both Bracers are on the higher difficulties, it's not uncommon for them to get multiple of these crafts off in a row before you can respond.
• Arianrhod, just like her student. What makes this fight especially fun is that if you look at the statistics, you'll assume it's another boss you don't actually have to beat to progress the story. It turns out that you do actually have to drop the boss down to 50% HP before your defeat will let you progress the plot. You're at a disadvantage of 25-30 levels, fighting a boss immune to all status conditions and debuffs and who has an S-Craft that is instant death. Reaching the minimum victory condition is difficult enough, actually winning for the DP bonus and EXP reward requires a very specific strategy, a lot of preparation and some luck. There's even an achievement for doing so.
• Campanella's fighting style could be summed up as "weaponised trolling". He loves to Teleport Spam; he sometimes swaps places with a party member upon being attacked, resulting in friendly fire; you can't use offensive Arts because he reflects all magical damage except that reflected onto him; and he frequently transforms a random party member into a pepper, rendering them only able to attack and move.
• Sigmund in your first fight against him in Azure. He states that you are supposed to beat him in 5 minutes. Just your typical stakes-raising, right? Nope, you have to beat him in 5 real-time minutes for maximum DP gain. In a turn-based strategy game. And if you're playing the Geofront patch, you can't even rely on turbo because that speeds the timer up. Keep your finger on that skip button. You will need it.
• One thing that makes many of the optional, but must beat for full DP bosses annoying is that they are often fought at the end of an extensive cutscene. And the option to skip cutscenes wasn't added to the game engine until the Cold Steel era. So failure to beat one of those bosses means having to reload the game and watch those cutscenes again, over and over.
• The Final Boss of Azure and the Crossbell duology as a whole isn't joking about it's credentials. It has an attack that triggers upon receiving enough damage in a single attack which inflicts the Vanish status aliment on a random party member. This means that it even bypasses Burst, so you aren't even safe there. Also at 33% HP and lower, it will start the countdown for it's One-Hit Kill which is an instant game over as it cannot be guarded against in any way when it goes off, so you trigger Burst and spam Burst Orbs to keep him stuck and buy time, right? The earlier stated attack will still trigger upon receiving enough damage at attacks. This means that in a situation in where you have to give it everything you got, you still have to constantly backpedal to avoid getting your party wiped. And these are just the most notable attacks. It also has a Status-Buff Dispel that costs no delay, so say goodbye to your much needed buffs and Zero Field. Casting arts? It will impede you without question, which includes the Master Quartz's Area of Effect if it was in effect. Of yeah, if your party consists of an evasion tank, he will be hit by it without question as it's attacks are mainly crafts. While final bosses normally don't count for this trope, Azure Demiourgos is much harder than the final bosses of the Sky trilogy on equivalent difficulties because of its anti-cheese tactics.

The Legend of Heroes: Trails of Cold Steel

• In the first game, the final battles of Chapter 6 stand out as it's a Marathon Boss against two tough opponents who each have an S-Craft that can one-shot your party and have huge areas of effect. Both also have backup and an array of wide-area attacks that make it very difficult to keep Adamant Shield active.
  • The boss of Chapter 2, the two Kazakh Dovens, can be this due to their hard-hitting physical attacks and ability to buff themselves, as well as a Combination Attack that's nearly guaranteed to one-shot anyone in your party (and if someone somehow manages to survive, it inflicts Faint). Making things worse is that everyone in the Chapter 2 team is a Glass Cannon apart from Machias, and because Elliot is in Saint-Arkh, you don't have his extremely useful Resounding Beat Craft (raises defence and gives gradual HP regeneration) to fall back on.
• Laura and Fie's fight against Rean and Machias in Chapter 4 counts... for one reason only: Rean's S-Craft. He can use it with no warning and no wait time, there's no way to interrupt it and with the small arena it's always going to hit and one-shot both Laura and Fie. The fight is basically a coin-flip as to whether or not Rean decides to instantly make you lose at any given moment.
• Unsurtr, the boss of the 5th floor of the Old Schoolhouse. A large dragon-like boss just like the end boss of Chapter 4, which was surprisingly easy, so this should be the same, right? Hardly. Unsurtr not only has massive Strength and Defence, it's also really fast, has AOE on nearly all its attacks, and everything it does can Freeze. It's also heavily resistant or outright immune to every status except Blind, Nightmare and Faint, and this includes Delay and Stat Down, so many of the Game-Breaker tactics mentioned above won't work. Blinding it is the only saving grace you get, and even that's unreliable. Due to its speed, it's extremely difficult to come back if it KOs any of your party members, as it'll eat through your remaining members faster than you can revive them. It is entirely possible for it to get three-to-four turns in a row, and should you end up in this worst-case scenario, you're very screwed.
• Gordi Schnarr G in the sequel, which is only a normal sidequest target, manages to be this due to its Chest Beating. This move buffs the boss' Strength, Defence, Speed and heals it, turning it into a Lightning Bruiser and a Stone Wall. But it's made even worse by what the boss does when the buff almost wears off. It first uses a massive damage area attack, then it re-applies Chest Beating, causing all these buffs to stack up to 50% boosts. With +50% speed, the boss can use its area attack repeatedly without giving you a chance to cancel it, leading to a Total Party Kill very quickly. You know it's bad when most walkthroughs recommend Nightmare Mode-level strategies for this fight and tell you to simply spam S Crafts on it once its HP falls below half.
  • The Order of the Lion can be this in the second game. They're as close as you can get to a Mirror Match in this game, meaning they can use many of the same Game-Breaker strategies you can, like Delaying/Cancelling, buff stacking and powerful arts. And if you're going for the 100% battle book Trophy, you need to scan all of them, giving them several turns to buff. Edel in particular is one of the most brutal, as she can cast very powerful Arts like Adamantine Shield, Crescent Mirror and Seraphic Ring (a full heal and revive on the whole party). Let her get a few of those off, and it can be very hard to recover. The characters even remark on how scary she is in-universe.
• But by far the biggest and most infamous one is McBurn, who's essentially II and beyond's equivalent of the Chapter 6 fight with C in the first game. He has nearly twice as much HP as the previous bosses, takes half damage from all Arts (except Fire, which he's naturally immune to), is immune to all status except Stat Down and Delay... which has only has 10% vulnerability to, so he's a complete Stone Wall. Offensively? Flames of Judgement is powerful and also has a Status-Buff Dispel effect (one of the very few examples of that in the entire game, and buffs are necessary to beat him) and Hellhounds can inflict instant death. And those are just his basic attacks. His Purgatorial Flame Art can potentially deal double your maximum HP in damage, his S-Craft has a wide area and is pretty much a Total Party Kill, and as if that wasn't enough, he can use a Lost Art, Sol Eruption, which might as well be named "cancel this or it's an instant Game Over". And often, he doesn't give you the chance to. Overall, this is the kind of fight where you have to go all-out with every single Game-Breaker available to you to even stand the slightest chance of winning. And to add insult to injury, McBurn isn't even using 10% of his full power.
• Generally, Cold Steel III is one of the easiest games of the series, but this doesn't stop this trope popping up from time to time. Take Aurelia in her Ace Custom for example in chapter 3. The first fight against her with Class VII isn't that bad since players do have some supports from Altina and a second character and that the requirement to get the extra AP is to reduce her HP to 50%. It's when she challenges both Rean and Randy inside Valimar and a Hector respectively is when things get hairy as they can only rely with one another with no supports from other characters (which means no refilling HP-CP and EP from any support except by themselves which will guarantee them wasting turns). While both Rean and Randy have a permanent 75% buff to their stats, it might as well have almost been non-existent as Aurelia deals a lot of damage against them, especially when she manages to get an additional link attack. Enough unlucky rolls and Aurelia might pull off a Total Party Kill with her 5 BP move.
• For such an early boss, the Stratos Diver in Chapter 2 of III is an absolute menace. It can easily hit your entire party for catastrophic amounts of damage and many of it's moves will cause various kinds of status ailments making it an even bigger pain. One of it's moves, Hyperactive Discharge, hits the entire field, can cause mute, and can shave off as much as half your life-bar, and that's if you're lucky. And then to make matters even worse, it is also fast as sin allowing to act with painful frequency. And should you manage to bring it down to half health it will Turn Red and gain Overboost that will give it even more actions as well as a new move that will likely be a One-Hit Kill if it's allowed to go off. And due to how often it is allowed to act, chances are it will be next to impossible to interrupt it. This all adds up to make it one of the hardest, if not the hardest bosses in the game.
• While you're not required to win, Rean's one-on-one fight with Wallace Bardias, also in Chapter 3, is another painful fight. He'll frequently put himself in Awakened status, buffing his strength (read: all his attacks 2-shot you) and healing him, and with Rean alone it can be hard to Break him before it wears off. This fight is difficult even if you're trying to cheese it with a Game-Breaker evasion tank setup, since him using a spear means Rean needs to be almost directly adjacent to him to be in counterattack range, which often leads to wasted turns repositioning, especially as the knockback from your own attacks can easily push him out of Rean's tiny counter range.
  • The Ironbloods are the only remotely challenging fight in the third game's final dungeon, admittedly in part because you've lost access to most of the game-breaking party members by the time you get to them. But they're no slouches on their own, with uneven HP stats that make them hard to take down all at once (meaning you're more at risk of S-Crafts), some dangerous Crafts including a full party buff from Rufus, access to link attacks and Rush, and finally Rufus' effectively-unblockable S Craft (see above).
• Cold Steel IV has a few that could be considered as one of these if the players aren't careful/it's a Sequential Boss fight that the player isn't totally prepared for. Take for example the boss fight against Rutger, Xeno, and Leo. By itself, it isn't that bad except this is similar to the turn limit boss fight with Xeno and Leo back in Cold Steel II, they're all ARCUS linked so they will get extra attacks in and if they gain enough Brave Points, they will use Rush attacks. Rutger is also built like a tank this early in the game and players are required to reduce their HP to a certain point in less than 40 turns. It doesn't help that the players had to deal with Gilbert and his jaegers in the previous boss fight which, while not hard since it's Gilbert, could leave players unprepared for the next boss fight.
• The last fight in the Black Workshop in Cold Steel IV also qualifies. Sequential Boss doesn't begin to cover it. You're fighting Osborne and Arianrhod together after four previous bosses who are all decently tough in their own right. You have to get both their HP down to a certain point (see Luck-Based Mission above for the details). Osborne can inflict nasty status effects on you, heal himself, and fling your party to the far corners of the room to mess up your formation. And they're ARCUS-linked, so they can link-attack you and even use Rush attacks. You have 313,665 HP to eat through for the bonus AP, so they're also significant damage sponges that you can't simply get a quick victory on. And worst of all, you have no chance to prepare beforehand thanks to the Sequential Boss rush; sure, you can save before the fourth boss in the gauntlet and the party is healed between fights unlike between Gilbert's squad and Zephyr, but you can't change your party's equipment or quartz, so the fight can become nigh-unwinnable if new Class VII isn't optimized, and the between-fight full heal doesn't replenish BP, forcing you to be conservative with BP in the tail-end of the fourth boss if you want to be able to tank their attacks with Brave Orders.

The Legend of Heroes: Trails into Reverie

• The (proper) second phase of the final battle, Zoa Gilstein piloted by Ishmelga-Rean, is hands down the hardest fight of the game. Unlike in Cold Steel III and IV where players can get equipment and buy items for the Divine Knight fights, Reverie lacks such a thing as, just like the Final Boss fight of Cold Steel I, the Divine Knight battle system was not used in the game until this point. Now as for the boss himself, he has a basic attack that hits three times and each hit inflicts damage, shredding most health bars easily, he has an attack that deals the dreaded All Cancel to all three pilots (Rean, Crow, and "C"), and he has a ridiculous health especially on Nightmare and Abyss difficulty (to put this into perspective, the Final Boss has 1.5 million hit points on Nightmare. Zoa Gilstein? 4 million hit points). And unlike other bosses, Ishmelga Rean exalts twice; once at half health and another when he's nearly dead. And anytime he exalts, he improves his already powerful strength and speed, and becomes immune to strength and speed debuffs. This means that he can pull off his Limit Break twice at minimum. But worst of all, he cheats on the mech fights by having a decent chance of dodging its weak points even at 4 stars. The only way to get around that is to rely on arts and crafts, but this is a Morton's Fork because those consume resources needed to survive in the first place and crafts have very high delay in the Divine Knight battle system. The earlier Hopeless Boss Fight segments where you have to knock him down to a certain HP threshold are also pretty tough, since you don't get to use items during those. Have fun.