10 Hardest Bosses In Final Fantasy History

Seymour Flux lives in infamy among fans for being one of the most frustrating bosses in the entire franchise. And mind you, it's in steep competition with... itself, frankly. Every Seymour boss is teeth-grinding for its own reasons, but Flux is the worst of the bunch. 

Flux gains its difficulty from two attacks. One is Full-Life, a healing spell that Seymour will use after afflicting a party member with the zombie status. Of course, getting hit with a healing spell while afflicted whilst technically undead is an instant death. The second, and the one that breeds such intense hatred among players, is Total Annihilation. This attack is essentially Seymour deciding that you weren't listening enough to that long, unskippable cutscene that led into this fight, so you should go back and watch it again. It isn't really an Insta-kill move, but it might as well be. 

The trick to beating Seymour Flux is two-fold. First, you should have Yuna constantly summoning Aeons. This gets off one good hit on him, and his Banish move - which removes Yuna's Aeons from play - eats up his turn for that round, thus putting off Total Annihilation. The second is to spam every move that inflicts silence and poison until they take. You can beat him without these two steps, the same way you can scale the Eiffel Tower using nothing but your pinkie fingers. Just because you can, doesn't mean you should.