Exorcistic Radiation

You concentrate necrotic energy from the abyssal plane releasing it in a burst from your point outwards. It reaches from 5ft., of you out to 20ft. All enemies within 20ft of you must roll a DC15 Dexterity (acrobatics) check or be knocked prone, hovering or flying enemies get knocked 20ft back from the point of impact. This attack does 4d6+3 necrotic damage. Enemies with holy protection or radiant gear don’t take damage from this. If an enemy is reduced to 0 hitpoints by this they become a mindless slave to you, with 1 hit point and 10 AC. Hitpoints increase by 2 for every spell slot, damage also increases by 1d6 each spell slot.