You can use your action to emit a deathly aura of necrotic energy that causes the veins of nearby foes to burst and bleed. For 1 minute, any hostile creature with blood that moves within 30 feet of you for the first time on a turn or starts its turn there takes 3d6 necrotic damage. If a hostile creature with blood regains hit points while in the aura, it regains only half as many hit points as expected.
Once you use this feature, you can’t use it again until you finish a long rest.