Araquirock

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.

Spider in the Rough: While the Araquirock remains motionless, it is indistinguishable from an ordinary rock or pile of stones.

Basalt Barge. Melee Weapon Attack: +5 to hit, reach 5 ft., one creature. Hit: 7 (1d8 + 2) bludgeoning damage

Web (Recharge 5–6). Ranged Weapon Attack: +5 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 12 Strength check, bursting the webbing on a success. The webbing can also be attacked and destroyed (AC 10; hp 5; vulnerability to fire damage; immunity to bludgeoning, poison, and psychic damage).

Cave In. Melee Weapon Attack: Dexterity Saving throw to hit, DC 14, one creature. Hit: 9 (1d12+2) Bludgeoning damage. The Araquirock jumps down from the ceiling and onto another creature. The target must make a Dexterity saving throw,  taking 1d12+2 and is stunned until their next turn or target takes half as much damage and is not stunned on a successful save. This creature is now on the floor. This can only be used if the Araquirock is on the ceiling above the target creature.