-When the battle begins, run the opposite way of the mist shooting out of the grates. Jump over when needed. Sebastian will not jump, thus burning himself. In his second phase, you must be directly behind one of the mists and follow it around until it stops. When he grabs onto the wall, put the purple portal object between you and him. He will run directly into it. Do this three times to proceed. In his third phase, he will try to destroy the stone. Jump up there so he gets off and charm the peasant in the room to unload all of the mist on the ground. His fourth phase is just a fist fight until the end.
-Let Sebastian kill you once, then allow the game to idle and watch the "steam" appear and kill Sebastian.
-At the start, block his attacks and watch out for his red attack. Be careful; after you knock him down, he will charge at you with an unblockable tackle. Just undo the Autoface and jump over him. Then, he will start to run around in circles while a column of thunder hits the center of the room. Run around the center while avoiding the dangerous gases from the side of the room. When you see him stop, this means he will strike. Stand in the room so that the column of thunder is between you and him. He will run into it, then leap back into the side. Repeat this about three times. Knowing he cannot defeat you, he will try to destroy the Nexxus Stone. Jump on top of the platform and use the Charm Gift on the guard that is activating the switches. Use him to operate one of the switches and draw Sebastian to you. Continue to attack until he is defeated.
-Whenever Sebastian charges at you, jump and use the fire attack. Get his health down to about one fifteenth, then he will charge up and will hurt himself eventually. He will take off half his health.