Chelicerae

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

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

Magic Resistance. The chelicerae has advantage on saving throws against spells and other magical effects.

Multiattack: The chelicerae makes one bite attack and two claw attacks.

Bite. Melee Weapon Attack: +9 to hit, reach 10 ft., one target. Hit: 17 (2d10 + 6) piercing damage, and the target is grappled (escape DC 16). The target must also make a successful DC 16 Constitution saving throw or become poisoned. If a creature grappled in this way attempts to cast a spell, that spell is countered as if by a Counterspell of the appropriate level and the chelicerae gains Nd6 temporary hit points, where N is the level of the spell cast.

Claw. Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit: 11 (1d8 + 6) slashing damage

Magic Drain. Melee Weapon Attack: If the Chelicerae is grappling any magical object, it can attempt to drain the magic from that object as if from a 3rd level dispel magic. Wisdom is it's spellcasting ability for this. If any effect is ended this way, the spider gains Nd6 temporary hit points, where N is the level of the spell cast.

Once per long rest, the Chelicerae can cast Counterspell(3rd Level) as a reaction. If the Counterspell is successful, the Chelicerae gains Nd6 temporary hit points, where N is the level of the spell cast.