Seymour Omnis

The final battle with Seymour Guado, the battle against Seymour Omnis, is staged Within Sin. Seymour's plan is to gain control of Sin from the inside to wreak havoc on Spira, but how he managed to get inside it is never addressed in the game.

Strategy
Seymour Omnis hovers in the air in front of four discs called Mortiphasms. As each disc rotates, the colored sections determine which spells he will cast at the party each turn. If each color is the same, the spells will have increased power. Seymour's magical weakness is determined by whichever side is furthest away from him when he is attacking. After each attack, the discs will rotate so a new spell is used. As the discs are facing the same way at the beginning of the battle, one of the first actions should be to forcibly rotate one by attacking it; this will prevent a barrage of powerful spells. Physically attacking a Mortiphasm will rotate it to the left, and using magic will rotate it to the right. The Mortiphasms, unlike Seymour, are out of reach, so only Wakka can attack them physically.

After six rounds, Seymour will begin casting multi-Dispel followed by Ultima that can potentially do over 4,000 damage to all characters. By this point, Lulu should know Doublecast and Flare, and Yuna will have obtained Holy; both can be used to great effect.

The player can let Yuna's aeons do the work; unless Seymour is using Water spells, it is possible to just summon the corresponding elemental aeon who will absorb the spells.

Another method is to use Armor Break on Seymour and then summon Anima in Overdrive mode and simply have her perform Oblivion, as this will deplete well over 50% of his HP.

An alternate strategy is to have Auron use Armor Break on Seymour. Because of his relatively low HP, a single hit from a high Strength character with a Break Damage Limit weapon will also kill him.

A final option involves casting Reflect on all party members and continually attacking the discs physically so they never line up. In this way, Seymour never receives full immunity, so every time he casts a spell it will bounce back and damage him instead, meaning you can sit and watch him kill himself.

Related Enemies

 * Mortiphasm
 * Seymour
 * Seymour Natus
 * Seymour Flux