Maniacal
the green Napoleon
Harder difficulties makes the witch startle easierly, but since she more often than not sits in your path at a choke point you can't avoid her. Have someone stand way back and shoot her, and everyone else open fire once she is startled and starts chasing him. Crouching may or may not help. Cr0wned is tricky, but try to sneak up behind her with an auto-shotgun.