- last post: 01.01.0001 12:00 AM PDT
In the epilogue when the high prophet is talkin to the brute, the brute gives him the remaining shards of the blue crystal that was found on reach. The prophet instructs the brute to reward the pilots that found the peices but then execute them "Quickly. Quietly.". After this the prophet makes a comment about how soon they will not need any more artifacts from "the great ones" whichi im going to assume refers to the forerunner. The prophet then says "the great journey shall soon begin......and let nothing in the universe impeed our progress".
So basically i think the covenant are going to try and transport the entire covenant race, or a large contingent back in time to either the forerunner's time or at a time when they would be able to destroy the Humans, or earth. This would explain the need for the blue crystals which can do stuff with time and space. As well, maybe its going to be just the brutes and the prophets sent back in time, as the elite honor guard was sent out of the room right before the brute and the prohpet began to talk.