Your warlocks should call for damage for the rest of your casters on Vek’lor, otherwise mages can easily rip off of them because they’re in full damage gear, while the tank is in survival gear.
We use 3 warlocks, and have finished the fight with our backup when the main tank died (since Vek’lor can hit incredibly hard unresisted).
Lastly, wherever you decide to tank them, make sure the warrior can still be the closest to them on the swap without triggering Arcane Explosion.
The fight is rinse and repeat, and the tank swaps are crucial. Once you can keep tanks alive and handle the swaps, the fight is very rinse and repeat.