Chelicerae

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

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

Bite. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 17 (2d10 + 6) piercing damage, and the target must succeed on a DC 15 Constitution saving throw or become poisoned for 1 minute. If the target is a Medium or smaller creature and the chelicerae doesn't have another creature grappled, the target is grappled (escape DC 15). A poisoned target is also unconscious while poisoned in this way. The poisoned target can repeat the saving throw at the end of each of its turns, ending the poisoned condition on itself on a success.

Claw. Melee Weapon Attack: +9 to hit, reach 10 ft., one target. Hit: 15 (2d8 + 6) slashing damage.

Magical Discharge (Recharge Special). The chelicerae releases some of its stored magical energy in a burst. Each creature within 15 feet of the chelicerae must make a DC 15 Dexterity saving throw, taking 36 (8d8) force damage on a failed save, or half as much damage on a successful one. After using Magical Discharge, the chelicerae can't do so again until it successfully siphons magic from a creature or until it finishes a long rest.

Spellcasting. The chelicerae casts one of the following spells, requiring no material or verbal components and using Intelligence as the spellcasting ability (spell save DC 15): At will: mage hand, minor illusion 1/day each: haste, hold person, invisibility, phantasmal killer

Nimble Moves. The chelicerae takes the Dash or Disengage action.

Siphon Magic. The chelicerae siphons magic from a spellcaster it is grappling. The target must succeed on a DC 15 Intelligence saving throw or lose one spell slot of the highest level it can cast. The chelicerae then regains an expended use of its Spellcasting.