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

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

Ambush Strike. Once per turn, the spider can deal an extra 2d6 damage to one creature it hits with a bite attack if it has advantage on the attack roll. Additionally, if the target would make a Constitution saving throw against the spider's poison, it does so at disadvantage as the Skulker Spider floods the creature's system with venom.  

Bite. Melee Weapon Attack: +8 to hit, reach 5 ft., one creature. Hit: 9 (1d8 + 5) piercing damage, and the target must make a DC 15 Constitution saving throw, taking 16 (4d8) 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.