Any luck yet? You should be able to use you interrupts, and if he casts again while your interrupts are on cooldown, have you tried force push (assuming he's not immune), also you can pop your defenses. If you have Light 5 alignment, you have an amazing new "oh crap" button. If not, perhaps some temporary buffs that are different than what you use? Some cantina vendors sell ones that add to presence that stack with stims for other stats, for instance.