Gathering a force to fight one individual is not a cost effective way to fight her. The ideal way to deal with her would be a dimension lock, followed by a force cage, followed by walling her in and killing her with some effect. The issue is that the dimension lock would need to be set on the ground in some way. I have never seen Dantie get hit with a friendly arrow, but then again, friendly fire isn't, so my opinion may be a bit biased. I think he is afraid to fight without all his fancy buff spells.
Yes, that is a rather roundabout way to kill someone, but hey, I didn't want to be too cheesy, and any method that involves a force cage, a dimension lock, a stone wall(non-porus), and some sort of kill method(burying her, drowning her, suffocating her, cloudkilling her...), is never going to be accused of being cheesy. Cutting her, and casting some sort of purify water effect, on the other hand, is very cheesy.