Magic Resistance. Ker-arach has advantage on saving throws against spells and other magical effects.

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

Web Walker. Ker-arach ignores movement restrictions caused by webbing.

Multiattack. Ker-arach makes one Bite attack and two Claw attacks.

Bite. Melee Weapon Attack: +9 to hit, reach 10 ft., one target. Hit:10 (1d10 + 5) piercing damage plus 13 (2d12) poison damage.

Claw. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit:12 (2d6 + 5) slashing damage.

Spiderling Breath (Recharge 5–6). Ker-arach exhales venomous spiderlings in a 30-foot cone. Each creature in that area must make a DC 15 Dexterity saving throw, taking 33 (6d10) piercing damage and 33 (6d10) poison damage on a failed save or half as much damage on a successful one.

Stifling Webs (Recharge 5–6). Ker-arach spins a 30-foot cube of strong, sticky webbing in an area adjacent to itself. The webbing lasts for 1 minute, is difficult terrain, and lightly obscures its area. A creature that starts its turn in the webbing or enters the webbing for the first time on its turn must succeed on a DC 15 Dexterity saving throw or have the restrained condition while in the web. As an action, a creature can free itself or another creature from the web by succeeding on a DC 15 Strength check.

A 5-foot cube of the web is destroyed if it takes at least 10 acid, fire, or slashing damage on a single turn.