A huge round rock

Area: Olympus

At olympus, hunt zeus first. When you reach the room "The Throne" where Zeus is, go 7 down and you will see charon the ferryman. Hunt and kill cerberus first and get the adamantite key to unlock the first gate southwards. From here u need to hunt polydegmon (to get the key to the realm of hades). With "the key to realm of hades", hunt Sisyphus and the rock you're finding will be on the ground. Sisyphus is not aggro, but the mobs along the way are.