User blog comment:Jarcellon/Soul Farming Locations/@comment-1852943-20130403155906/@comment-6230603-20130404041420

Once you reach SL 130+ farming phalanxes in NG, you might want to consider progressing on and finishing the game, then returning the same spot in NG+ and contiune farming.

And like what brainwasher, Volknur and Undead Chilla said, fire tempest/storm/chaos tempest works best. But in order for you to acquire these spells, you must have certain requirements. For that, might i redirect you to Quelana of Izalith ?