Seymour Flux

The third battle with Seymour occurs after Yuna and her Guardians make their way up Mt. Gagazet to get to Zanarkand. The Ronso try to stall the unsent Seymour, and stop him from reaching them, but to no avail; he kills nearly all the Ronso easily.

Seymour finally catches up Tidus and Rikku, and reveals that he has discovered the truth about Tidus' father being Jecht, and that he plans to unravel the mystery of how Jecht became Sin, to become Sin himself, and thus, destroy all of Spira to fulfill his ambition to "save" it. When Tidus and the rest of the Guardians stand down to fight, he summons a seemingly robotic being, upon which he sits. The Mortibody, this time known as Mortiorchis, fights with him.

Seymour Flux can use the attack Lance of Atrophy to put an ally into Zombie status, and the Mortiorchis will combo with Full-Life, effectively KO'ing a character (unless the characters have high Agility, as well as many Holy Waters). Like Seymour Natus, he can also Banish an Aeon, giving it approximately one turn to attack if summoned. He occasionally casts Protect and Shell upon himself.

Three turns in, Mortiorchis will start to use Cross Cleave, which deals around 2000 damage to the whole party. Seymour will then do a cheeky move, where he casts Reflect on himself and then rebounds Flare at a party member. However a character with high Agility or in Haste may get a turn in between and can Dispel Seymour, causing him to cast the spell on himself. Unfortunately, it doesn't do much damage to him. If Yuna has learned Holy it should do considerable damage. But not much other magic will be of any great effect, therefore melee attacks are the way to go and characters with the Piercing ability are most useful.

The most deadly attack is still to come: Total Annihilation, which requires 3 rounds of charging, and will kill anything but an extremely good party. It is recommended to cast Shell (not Protect) on all high-HP characters before he executes this. If you get the chance it may be necessary to sacrifice an Aeon in this case.

After Seymour's third defeat, he disappears, seemingly absorbed into the sky. However, his cruel murders of the Ronso would later foster great enmity between the Ronso and the Guado