Crab Spider

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

Camouflage.  These spider's lacking the webs of their kin, instead rely on their chameleon-like ability to blend into their surroundings. This acts as an invisibility spell that they can cast on themselves only after a successful stealth roll.

Bite. Melee Weapon Attack: +5 to hit, reach 5 ft., one creature. Hit: 7 (1d8 + 3) piercing damage, and the target must make a DC 11 Constitution saving throw, taking 5 (1d8) 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, the target is stable but poisoned for 1 hour, even after regaining hit points, and is paralyzed while poisoned in this way.