They could have spawned 2-3 supplicants there once the Templar got to half health. Heck, they could have teleported him there, towering over the puny mortals who thought they were so clever. Or on one of the other platforms to either side where players have no cover. Doesn't that sound better? There is a spot in the Devils Lair strike where Sepiks can't hit you reliably and had to rely on his adds. But every once in a while, he will teleport directly above you, and that powerful vortex thing will fire point blank while you try to figure out what happened and desperately bolt from cover straight into a pack of fallen adds. It's great and suddenly adds a challenging new dimension to one of the easiest strikes in the game.