The Bone Crusher is a booby trap, that also serves as the passage to the underground chambers of the Palace of the Fates.
There is a large chain in the middle of the chamber, and Kratos must grab it and pull it down hand over hand to make the platform descend. As he does however, a spiked ceiling also descends, and a large horde of Cursed Remains awaken. Kratos must keep pulling the chain to lower the platform and stay ahead of the descending ceiling. As he does however, he must also kill the Cursed Remains, who attempt to stop him from descending. If he succeeds, then he will be able to move on to the Phoenix Chamber.