All hell breaks through from here onwards. It combines aspects from what has been done previously. Heavily suggest picking a number 'G' to be, and stick with it. Try not to deviate from role as it'll be confusing as hell.
Getting the first relic
G1, G2 and G3 go in the left gate and while in there...
For G4, G5 and G6 (those at the sync plate)
the people outside MUST defend the sync plate and ensure that the Praetorians don't get control of the plate. If they do while the players are inside the timegate, they get stuck inside, become "Lost in Time" and everyone dies. Must stay open until the gate party exit.
For G1, G2 and G3 (those who enter the gate)
After killing the Gatekeeper and picking up the relic, these three need to exit as soon as possible from the same side of the gate. When they exit, they must stand still so the relic carrier can hold L1 and cleanse off the "Mark of the Void" debuff which is gained when relic becomes active in the Timegate. When the debuff comes off, the relic carrier and one of the other two in the trio need to go in the right gate.
Getting the second relic
G3, G6 - defend the conflux from the Minotaurs
G4, G5 - defend the other sync plate to ensure the Praetorians don't enter
G1, G2 - after entering the second gate, the carrier needs to launch super, making sure to hit boss in middle. Partner use rockets and grenades to kill off the rest and push Gatekeeper up hill. When screen starts to get dark, relic carrier uses L1 to cleanse then continue assault.
Once second relic is obtained, get out as safely as possible (if either is dropped, party is wiped out) and entire raid party should group up on conflux and dispatch enemies until phase is concluded.