The Call of Anwynn

Arawn channels His power through your form. A black skeletal hand bursts through your chest, clutching at the opponent you intend to harm. You utter a word of power that can compel one creature you can see within range to die instantly. If the creature you choose has 100 hit points or fewer, it dies. Otherwise, the spell does the full 100 hit points damage on any D20 roll above 15,  by 90 for any roll between 10-15, or 75 for any roll under 10 (crit fail inclusive). 

Using this spell, however, comes at a cost. You are reduced to no spell slots and will be rendered unconscious until Arawn releases you.