Final Battle, Round one
You’ll need to defeat Gabranth again before you can reach the final boss. You might be able to Blind him, which makes the battle considerably easier; otherwise, you’ll need to handle him the same way you usually handle powerful attackers. Use Bubble, Protect, Haste, Regen, and Decoy on a high-HP, high-Defense character, then allow him to take the brunt of Gabranth’s attacks.
Final battle, Round two
Open the first round of combat with the final boss with a battery of high-powered area-effect spells, thus damaging and hopefully destroying his Sephira backup. If you’re around level 50, this can be a dangerous, challenging battle, as the boss is capable of throwing both elemental spells and lethal counterattacks. You’ll have Gabranth on your side during this fight, though, which helps a great deal.
Final battle, Round three
The last boss of FF12 doesn’t have a health bar. He will, however, use an invincibility effect at 75%, 50%, and 25% of his life. Dispel his Haste effect, then unleash everything you’ve got. The boss can fire back with some of the most potent spells and skills in the game, so it’s important to keep your HP high and your buff spells flowing. If you’re about level 55, you should be able to take him down and beat the game!