Black Hand

Billowing Smoke. Emerging from the Black Hand in a 15 foot radius is a thick, dark billowing smoke that obscures the hand within and forces disadvantage on striking the hand. The smoke can be temporarily removed by a strong gust of wind (like from the gust or similar spell).

Realm Jumping. The Black Hand has the unique ability to jump through the realms and invade personal pocket dimensions of spellcasters. In order to perform this act, the Black must past a Charisma Saving Throw with a DC of 8 + Spell Level + Caster's spell modifier.

Multi-attack. The Black Hand can perform three Necrotic Slash attacks.

Necrotic Slash. Melee Weapon Attack: +15 to hit, reach 5 ft., 1 target. Hit: 24 (3d10 + 6) slashing damage and 14 (4d12) necrotic damage

Poison Mist. Originating from the palm of the Black Hand, a 30 foot cone of poison mist emerges and each creature caught in the spray must make a DC 25 Constitution Saving Throw or take 12d12 of poison damage and gained the poisoned condition. Half as much damage on a success and is not poisoned. Regains use of this ability on a 5-6 on a d6. 

Teleportation. As a bonus action, the Black Hand can teleport up to a range of 90 feet.

Necrotic Slash. Melee Weapon Attack: +15 to hit, reach 5 ft., 1 target. Hit: 24 (3d10 + 6) slashing damage and 14 (4d12) necrotic damage