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.

Limited Telepathy. The arachnid can magically communicate simple ideas, emotions, and images telepathically with any creature within 100 feet of it that can understand a language.

Reflective Thorax. Any time the arachnid is targeted by a magic spell roll 1d8. On a 2, the arachnid is unaffected as the spell reflects harmlessly. On a 1, the arachnid is unaffected, and the effect is reflected back at the caster, turning the caster into the target.

Detect Sentience. The arachnid can sense the presence and location of any creature within 300 feet of it that has an Intelligence of 3 or higher, regardless of interposing barriers, unless the creature is protected by a mind blank spell.

Multiattack. The arachnid makes two attacks as a part of the Attack action.

Bite. Melee Weapon Attack: +7 to hit, reach 5 ft., one creature. Hit: (3d8 + 1) piercing damage, and the target must make a DC 11 Constitution saving throw, taking 7 (2d6) poison damage on a failed save, or half as much damage on a successful one. If the saving throw fails by 5 or more or the damage reduces the target to 0 hit points, the target is stable but falls paralyzed for 1d6 hours. 

Leg.  Melee Weapon Attack: +7 to hit, reach 10ft., one creature per leg.   Hit: 3d8 +3 bludgeoning damage, and the target must make a DC 12 Dexterity save or be knocked prone. 

 Web (Recharge 5–6). Ranged Weapon Attack: +7 to hit, range 30/60 ft., one creature. Hit: The target is restrained by webbing. As an action, the restrained target can make a DC 16 Strength check, bursting the webbing on a success. The webbing can also be attacked and destroyed (AC 12; hp 10; vulnerability to fire damage; immunity to bludgeoning, poison, and psychic damage).