Instructions
Clear the rocks, vines and other obstacles from Gaia's heart by using the Cestus. Once Gaia's heart is clear begin attacking it; this results in green orbs to restore Kratos's health. Continue attacking the heart. Once Gaia has been hurt enough Zeus returns.
Dodge Zeus's attacks throughout the fight. Zeus begins this stage of the fight by immediately hurling lightning. He then focuses primarily on circling around and launching ghosts toward Kratos that can be blocked or parried. He also uses a three-hit combo similar to that used earlier in the fight, which again can be parried. Use a double-jump and float to dodge when Zeus uses his bomb attack.
Attack Zeus using light attacks with the Cestus, dodging his attacks when necessary.
Strike at Gaia's heart when it glows red. This gives Kratos a slight health boost. Don't worry about Zeus healing himself and focus on continuing to strike at him with the Cestus as he floats above the ground by holding the "Square" button for a barrage attack.
Defeat Zeus's clones as he summons them. They use a three-hit combo similar to that of the boss so avoid their attacks. Use the Cestus to stun and knock back the clones. Continue across the room toward Zeus, using the Cestus to defeat the clones and dodging the lightning attacks. Three shots should drop each clone.
Focus on attacking Zeus. Even when Gaia's heart glows red continue attacking Zeus instead of the heart. After a while Zeus begins summoning three clones at once. Position Kratos in front of all of them and use the Cestus magic to kill each clones and resume attacking Zeus. Use the barrage attack (hold "Square") to stun Zeus anytime he charges for the heart.
Use the Cestus magic to defeat clones as Zeus begins to summon more of them. When low on health Zeus summons at least five clones at once. Clean them and continuing attacking. Focus on dodging attacks and striking at the boss and not on replenishing health. Continue this until entering the Quick Time Event which takes Kratos and Zeus out of Gaia's chest.