Returning all 7 Millennium Items to the stone tablet, along with the 8th key, will release Zork. The 8th key is the Pharoah's name, which is why he had it erased from history and chipped away from the stone tablet on display in the museum in the future and erased his own memory, so no one could ever learn it and release Zork again. Bakura has to find it now, in the past, before it was erased.
I'm so mad! No one treats thief Bakura like that and gets away with it! Zork is pure evil and needs to be taken down! I can't believe Aknamkanon blamed himself for the creation of the Millennium Items. It was all Aknadin's fault - Aknamkanon didn't know what he had in mind, just that he was going to protect Egypt. Chibi Atem flashbacks were cuuuuute!