Amulet of Supremacy

This amulet is often found in the hands of cruel rulers, used to perform summary executions without lifting a finger. 

This item has 4 charges.

Whenever a creature within your sight falls to a hit point value that is less than your player level, you can use your reaction to expend one charge and cause them to make a DC 15 constitution saving throw. On a failure, the amulet reduces the creature to zero hit points immediately. You can expend more charges with one use, with each additional charge used increasing the DC by 5.