Bolt of Unforgiving demise

You expend your life force to emit a bolt of green energy that saps the life from everything it touches. Each creature in range of the spell that has less than 500 hit points dies immediately. If the creature has more than that they must succeed a DC 28 Constitution Saving throw or take 25,000 necrotic damage, this damage ignores immunity. If the creature survives, it loses all it's experience points and is reduced to level 1. You must die to cast the spell, and any means to bring you back fail. Your character simply ceases to exist