Capture soul

You stare directly at a creature with abyssal black eyes, forcing the target to make a spell save DC. On a failed save, the target's soul gets reaped from it's body and stored in your diamond material component. On a successful save, the target takes 50 necrotic damage. If this damage kills the target, the same thing happens as if the target failed the saving throw. Your diamond can hold up to 5 souls at a time. If your diamond gets destroyed, the souls contained inside are released into the afterlife. The same occurrence happens if a Wish spell is cast Specifically on the diamond and is meant to free the souls. If dispelled, to diamond converts back into a normal gem.