Final Fantasy V bosses sure are... designed. JRPGs have this reputation for being beatable through pure grind, but no amount of hit points would have saved me here.
Boss's moves:
Hit someone a little (hope for this I guess)
Hit everyone pretty hard
Confuse (mind control) someone (this can be resisted - the rest cannot!)
Paralyze someone, drain their intelligence, and make them bleed (it's a "mind blast" though??)
Just remove all but a handful of someone's hitpoints
The last two make a particularly gruesome combo. Well the last one is brutal at the best of times, but it's a death sentence for a bleeding character. And neither appear to grant a saving throw. The boss randomly decided on the excellent tactic of paralyzing 3/4 of my part then removing all their HP. My regenerating berserker flailed a while before dying similarly.
But how did the boss get so many actions? Well, it has three invincible mirror-images which share all its powers, of course. You have to guess which of the four to attack, and it changes every time you get it right (and also randomly).
What's that? You used an area of effect? Nah that's cheating, eat four massive AOEs for your trouble. Should have guessed the rules! Gods forbid any of this be hinted at in the game itself, you're just supposed to figure it out the hard way.
Whining done, now for solutions. The internet suggests spamming the Samurai's gold-throw, which works against almost anything, along with a frost shield to absorb the retaliation strikes. Somehow I don't have any frost shields though.
Ribbons should prevent the paralysis at least, but only one character learned the Equip Ribbon ability (ironically, the only guy in the party. FFV is kinda progressive in some ways). The ability comes from being a dancer, but dancers have AOE attacks that would get the party nuked.
Technically this dungeon is optional, I could just leave, but I've completely lost track of the main story after several months hiatus, heh. And I'm pretty close to victory. I can also learn that broken paralyze-drain ability with blue magic, and heck maybe it'll even work on some bosses? This game is weird that way.
Ah, the Genji glove and Genji helmet stop paralysis and confusion! So my knight's covered, and on healing/guard duty
Bartz goes "Freelancer" with Equip Ribbon and Rapid Fire, throwing the Rising Sun with monk strength and dancer speed.
My red mage equips Learning and a regeneration ring, hoping to learn Mind Blast and survive while throwing heals.
And my berserker gets a reflect ring just in case that actually works against anything (ought to work against Mind Blast at least...) along with duel-wielding knives. They're a pirate after all!
welp time to get my butt kicked again, but this was fun! Game is hard and unfair but does offer solutions.
Edit: half my party got ganked by Level 5 death by a random encounter between the boss and save point