Actually, you can use the middle platform. I think the splash damage comes from that rock wall on the middle platform. What works for me is that you should have the relic holder use the bubble at the front right hand corner of the platform so that the rock wall is not within the bubble. If you don't do it in the middle platform then supplicants will just come inside your bubble and wipe your team. Oh a great tactic is when the Time's Vengance buff is at 3 seconds or so left, you should have your Defender put up their Ward. This will make it so you all don't have to jump off the middle platform into a bunch of supplicants. Then you can just wait for the warp. Once your team is warped Atheon will freeze so you can get out safely. Just be sure to not stand directly in the middle of the Ward or you wont really be able to break your suppression field.