It was just a really quick video a guildie made of me spellweaving, yes I am a ToS, but we use the necro spellweaving animation (I assume we will get our own at a later date)

Have you even done the fight? Because your missing the point. You basically make sure your main tank has heals on him at all times, and when he starts taking to much damage, he kits him, so his hots have time to heal him up. The people are dead because he does a damage shield that reflects damage back to the player, which is almost impossible to tell when he does it until its to late.