This is the strategy that pretty much every group I ran with uses to beat ogres then Crota. Now they are using wall shooting to aggro the boomers to reduce wipe chance for sword bearer. Basically jump to the right tower. Walk along the ledge that boomers fire from while moving toward the back of the map. Hop over the rock wall and you will be in a nook with the rock and Crota to your back while facing and shooting the wall between you and boomers. It's not fool proof but it helps. Also works for any 31 running it.