Using garlic-based spells while in vampire form harms you. I think it only makes sense that using holy magic while in necro forms should harm you too. A change like this would immediately fix a number of exploits that are commonly used to solo things that weren't intended to be solo'd. It would also trigger a lot of people to complain, because it would mark a significant slice out of character power (which makes content actually challenging). For example, if you are under the effect of enemy of one and hit something with a leech effect from necro, the 2 abilities should counteract and prevent you from leeching the whole amount.