I personally think the problem lies in your healers. My group employs the mt on big snake, ot on 2 small snakes. During the dive bomb phase, I only need to pop foresight and it's enough to get me through that phase. We have never died on dive bomb phase, even while practicing. Of course, when tanking all 4 small snakes, the tank would put up hallowed since the damage can be huge and sometimes unpredictable. The ot should bring the snakes as close to the big snake, leaving enough distance to prevent stacks on the mt.

If hallowed ends and the 4 small snakes aren't dead, pop rampart and sentinel.

Oops I forgot to mention we still run a 2 pld setup. It could still work with warrior, I've done it before.