got it, tried it, parked it in back of the spell book.
average with dot aa's and crit aa's was between 6k and 9k damage per tic. generates alot of aggro. hugly mana ineffecient. with long fights you can either stack 6 dots and keep them on, or you can chain cast this one and the one you get at 87 and i promise you will be out of mana long before the first mob dies at 2500 mana per cast between the two of them. ocasionally you get a big number. btw twin cast only words on dd spells.
this would have been great 15 to 20 levels ago when the damage would have put a noticable dent in the mob for the amount of mana it usses. at 86 you are better off going for sustained damage by stacking dot then blowing your load to chain cast these. in just about any situation short of farming trade skill stuff in low level zones. grouping and boss mobs it is about sustained dps, soloing same.
not a good spell for grouping, soloing, raiding imo.