That they seem to be at war no matter what the dimension. Other than that, not much. I know the basics and anything that could have tied into outside of the box thinking for a spell or a potion. I know that witches have been known to call on either side to help cast their circle or for favors-usually the practioners but I've been known to tweak element spells for certain archangels. It isn't that all uncommon in the occult.