In this case, I simply used a manual rotation.

I manually hit flameshock, then I manually hit lava burst, then I hit my trinket/blood fury/elemental mastery/bloodlust key, then I basically manually did LB, LB, LB, LB, LB, LvB, LB, LB, LB, LB, LB, LB, LvB (I think about this time the boss was dead).