From Reddit
The majority of groups will stagger Oryx, then have the relic runner shoot at his chest, the roamer shoot at adds and the 4 others run for the orbs. Sometimes people die to adds, imo completely unnecessary.
After Oryx staggers, you have a LOT of time (about half a minute). As soon as he staggers, everyone stay IN the aura and just kill the adds. Spend a good 10-15 seconds, front guys shoot front adds, back guys shoot back adds. ToM on all players helps a lot. When adds are all dead, run to your orbs in perfect safety, detonate in sync (countdown helps) and run back, laughing at the 2-3 leftover thrall who have no chance in hell of killing you.
N.B.: One guy must keep shooting Oryx's chest to keep it open, so the bombs can do their damage. A single ToM spammed is enough.
There you have it. One phase of the fight made super easy.