Anti-Divine

You fire a beam of necrotic energy at a target, if the target is a holy spell, anti-divine cancells the spell.  if the target is a divine/holy being. it will be slowed down, poisoned. and the target is feeling really tired for as long as the spell lasts. the spell cannot be removed through holy magic, it can only be removed by the caster. if the caster has died. the spell stays for its full duration. whenever a necromancer tries to use this spell. the caster either takes 3d6 damage. or part of the casters body will rot away, leaving bone (the DM can decide which will happen) if the casters body has completely become bone the caster will become a lich. but 50% of the casters spell will be forgotten.