With a snap of your fingers, you burst the heart(s) of an eligible creature you can see within range. If the creature has a functioning cardiovascular system, it must make a Constitution saving throw.
On a fail, it drops to 0 hit points and its maximum hit points drop to 1.
On a success, it takes 6d6 necrotic damage and becomes stunned for 2 turns.   For a creature to be eligible, you need to have dealt necrotic damage to them within the last 3 turns.   Ascended Spell. This spell costs 2 Spell slots to cast. A 5th-level spell slot and a 4th-level spell slot.