The priestesses may be obese, but they can jump very long distances, which is why they are usually fought near platforms or ledges. On most platforms, the priestess will be unreachable for all but the Reds and the Overlord's Evil Presence spell. After taking some damage, the priestess will jump down clumsily and she can be attacked by all minions. After some time, she will cast a spell that will knock over the Overlord and his minions if they are near her. Then she will jump away and the whole cycle will start over again.