ok first off u don't really need that cube thing i beat the game without touching it so wat u do is try to get close enough to the archers so u can kill them with ur blades of chaos or if u have enough magic u can take em out with zues's thunder bolts then u hop up on the ledge(a double jump should do it) then u will run into some more archers and stuff (and i think a couple of those dogs too) well after u beat those go into the doorway and pull the lever then wait as the room thing turns (do not open the red chests) ok now wait until u see a place with wat i think has either a blue or green chest then go out and u fight some new enemys and then climb aloong the edge and there