Soul Gem

This glowing magic gem floats in the air, slowly rotating around you. As a Magic Action, you can spend 1 charge and the gem makes a blast of negative energy towards a creature that you can see within 60 feet. The target must make a DC 21 Constitution saving throw, taking 10d10 necrotic damage on a failed save, or half as much damage on a successful one. If the target reaches 0 hp, it immediately dies, its soul is entrapped within the gem, and it can't be resurrected, unless the gem is broken. This magic gem has AC 20, 50 hit points, and has Immunity to Poison, Necrotic, Psychic damage, and to Bludgeoning, Piercing and Slashing damage made with non magical attacks. Each time you spend a charge, you consume a soul trapped within the gem. The DM chooses which soul is consumed. If its soul is consumed, that creature can be resurrected only by a wish spell.

Recharge. This magic gem recharges 1 charge each time a soul is trapped within.

Proficiency: shield Source: Treasures from Oerth p. 40 (Homebrew)