As of right now, just managing to get to Atheons door, it's closed. Got all 3 memories, but I'm not sure if it'll open through some event, or again, just a troll. EDIT: Don't attempt to get to the door, unless you're meaning to explore. Looks like there's no way to get to the portal from here, and you revive by the entrance to Atheons room. EDIT 2: You can get back. There's 2 platforms at the very bottom of the portal area. You can land on these, and use the mountain to jump back up to the platforms.