The artifact is in the bottom of the shaft that was filled with water when you entered the room.
Artifact: Soldier 2
Make a portal in the ceiling, and another in the wall. In order to get onto the ledge where the artifact sits, you'll have to time your glide just right when popping out of the portal.
Climb up onto the ledge that goes around the edge of the room so you can make a charged portal on the top of the rock floating in the middle. Jump into any convenient portal to be launched up to the Champion artifact.
You will not be able to return to Eden as with other areas in the game (poetical, right?) so be sure to collect ALL the loot before you bail. Especially don't miss the Abyssal armor piece.
You acquire a full Lifestone when you enter Eden.
The chest is hidden under the staircase that leads to the tree of knowledge. Jump off the stairs to the left and glide down to solid ground, then duck into the cavern under the stairs.
Jan 15, 2010