Aracnoid

Spider Climb. The arachnoid 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 arachnoid knows the exact location of any other creature in contact with the same web.

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

Illusory Appearance. The arachnoid covers itself with a magical illusion that makes it look like the humanoid it transformed from. The illusion ends if the arachnoid takes a bonus action to end it or if it dies.

The changes wrought by this effect fail to hold up to physical inspection. For example, the arachnoid could appear like a humanoid, but someone touching it would feel a hairy carapace-like skin. Otherwise, a creature must take an action to visually inspect the illusion and succeed on a DC 20 Intelligence (Investigation) check to discern that the arachnoid is disguised.

Multiattack. The arachnoid makes two attacks: one with its bite and one with its claws.

Bite. Melee Weapon Attack: +4 to hit, reach 5 ft., one creature. Hit: 4 (1d4 + 2) piercing damage plus 3 (1d6) poison damage.

Claws. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 5 (1d6 + 2) slashing damage.