Black Hand Stalker

Mutated Climber. The Stalker can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.

Shadowed Form. While in dim light or darkness, the Stalker can take the Hide action as a bonus action, and it has advantage on Dexterity (Stealth) checks made to hide.

Corrupted Ambush. The Stalker has advantage on attack rolls against any creature that hasn’t taken a turn in combat yet. On a hit against a surprised creature, the attack deals an extra 10 (3d6) necrotic damage.

Abyssal Resilience. When the Stalker takes fire, cold, or necrotic damage, it can roll a d4 and reduce the damage by the number rolled.

Multiattack. The Stalker makes two attacks with its claws or daggers.

Claws. Melee Weapon Attack: +5 to hit, reach 5 ft., one target.
Hit: 8 (2d4 + 3) slashing damage plus 3 (1d6) necrotic damage.

Thrown Dagger. Ranged Weapon Attack: +5 to hit, range 20/60 ft., one target.
Hit: 6 (1d6 + 3) piercing damage.

Black Ichor Spit (Recharge 5–6). The Stalker spits corrupted bile at one creature within 15 feet. The target must succeed on a DC 13 Constitution saving throw or take 10 (3d6) necrotic damage and be poisoned until the end of its next turn.

Fade Into Shadow (Recharge 4–6). When the Stalker is in dim light or darkness, it can turn nearly invisible until the start of its next turn or until it attacks, casts a spell, or is exposed to bright light.