This is a fairly difficult strike, even with three players on our team above 660. The first two waves were no problem, but we kept getting caught on the two large knight stage. Thrall kept spawning all over and we were getting boomed by the knights. To remedy this, we found that going in the top left corner (in the way back left if your facing the center where boss spawns) gave us an opportunity to snipe/plink away at the knights and keep control of the ads. Just a tip for those struggling! Best of luck