The NM for this quest went down with relative ease.. It was a matter of getting it to 10% HP 4 or 5 times while I built up 300% TP, it would use Soporific and heal itself back to around 90%, and sleep me. I'd drop Stoneskin.. and still be getting hit for 0's. Phalanx alone is enough for this mob. Once I woke up, beat it back down to 20%.. unleash a 300% Spirits Within, and if it still has HP left, nuke like mad. I used Chainspell for my nuking, though it probably wasn't necessary.