This super dark violet, shadowy claws are tipped with a venom that is completely invisible to those that have not killed for an evil purpose, whether that be for fun or for greed or something else that is more serious. 

The claw has 2 charges. You can spend 1 charge to cast chill touch. You can spend 2 charges to pull a stream of shadowy, fiendish magic from the claw, causing the claw to teleport onto your largest finger. While this is active, you may use your action that turn to make an Unarmed Strike against a hostile creature you can see. On a hit, the attack does piercing damage instead of bludgeoning damage and the target must make a Constitution saving throw, taking 2d4 necrotic damage on a failed save, or half as much on a success.

Notes: creature that has killed another creature with evil intent at least once in their life.