Black Thrall

Spider Climb. The thrall can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.

Web Sense. While in contact with a web, the thrall knows the exact location of any other creature in contact with the same web.

Web Walker. The thrall ignores movement restrictions caused by webbing.

Vile Servant. The thrall has advantage on attacks against a target within 5 ft. of a Black Widow that it serves. 

Multiattack. The Black Thrall makes two attacks, one with its bite and one with its piercing leg. 

Bite. Melee Weapon Attack: +7 to hit, reach 5 ft., one creature. Hit:  16 (3d8 + 4) piercing damage, and the target must make a DC 13 Constitution saving throw, taking 12 (3d8) poison damage on a failed save, or half as much damage on a successful one. If the poison damage reduces the target to 0 hit points,  it dies. 

Piercing Leg. Melee Weapon Attack: +7 to hit, reach 10 ft., one target. Hit: 12 (2d8 + 4) piercing damage. 

Web (Recharge 5–6). Ranged Weapon Attack: +7 to hit, range 30/90 ft., one creature. Hit: The target is restrained by webbing. As an action, the restrained target can make a DC 14 Strength check, bursting the webbing on a success. The webbing can also be attacked and destroyed (AC 10; hp 5; vulnerability to fire damage; immunity to bludgeoning, poison, and psychic damage).