Just finished this quest as a lvl 44 with madness spec. Didnt have much trouble with Zash after upgrading Khem's mods and enhancements, but Thanaton was whooping my butt repeatedly. Checked here and found strat about using the rock column to LoS his spells and then it was a piece of cake. Don't think I even bothered using my own interrupts. Just ran around the post with Talos healing me and popping off dps when Thanaton wasnt casting something. No more wasting time running all the way back from the respawn point. Thank goodness!