I've carried scrubs thru, almost it was as good as soloing it. I was the only one inside, everyone else was outside shooting knights. my tactic, run out, use the solar nades to the crystal to pull the witches. get up into a boomer tower, IB the witches. if they are dodging or you feel rushed RL them (no ghorn for me), but try to save ammo. I tend to get the witches down before the shreakers spawn and I will try and pop a few ranged knights / acolytes. before tunning in to take out one shreaker then running to the other side and taking otu the other. then I will back otu to just past the door and try and take out some more ranged untill the main wizard starts to sing. then I will run in jump ontop of a door in the crystal room and IB the main witch while she sings. extremely easy to burn her down fast while she is singing cause she does not move. a black hammer may be even better but I've not tried it because my IB is always on.