Lich Breath Grenade

Shade of Death. As an action, you can activate this grenade and throw it at a point up to 60ft. away. The grenade explodes in a cloud of dark purple vapors that spread in a 20ft. radius sphere. The sphere spreads around corners, and its area is heavily obscured. It lasts for 1 minute or until a wind of moderate or greater speed (at least 10 miles per hour) disperses it.   When a creature enters the area for the first time on a turn or starts its turn there, they have to make a Constitution saving throw (DC 15). On a failed save they take 3d6 Necrotic damage. On a successful save they take half damage.   Undead creatures are unaffected by the cloud. Their senses are not obscured and they do not take damage. Additionally, they have advantage on all attack rolls while they are within the cloud.