Bone Crawler

Keen Smell. The bone crawler has advantage on Wisdom checks that rely on smell.

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

Multiattack. The bone crawler makes two attacks: one with its tentacles and one with its bite.

Bone. Melee Weapon Attack: +8 to hit reach 10 ft., one creature. Hit: 4 (1d4 + 2) poison damage and the target must succeed on a DC 13 Constitution saving throw or be poisoned for 1 minute. Until this poison ends, the target is paralyzed. The target can repeat the saving throw at the end of each of its turns, ending the poison on itself on a success.

Bite. Melee Weapon Attack: +4 to hit, reach 5 ft, one target. Hit: 7 (2d4 + 2) piercing damage.

Last Stand. Ranged Weapon Attack: +6 to hit, range 20/50. Hit: (2d12 - 2) bludgeoning damage. Can only be used if at 5 hit points or less. After this attack, the bone crawler must make a DC 15 Constitution save, or else drop to 0 hit points.