The Oath Stone of Orkos is an item that Kratos acquires at the end of Chapter 20 - The Gauntlet of Apollo. This item allows Kratos to create a clone of himself, essentially allowing him to be in two places at once. It is used to hold levers and other switches in place so Kratos can do something else.
In battle, the Oath Stone is used to summon a clone of himself, which then attacks the enemies. The first move it always does launches enemies into the air. For 5,000 red orbs, you can power up this item to level 2, which increases the attack time, as well as decreasing the cooldown time so you can use it again.
