Multiattack

The bone collective makes two claw attacks, or one claw and one bite attack, or one swarm attack.

Bite

Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 31 (4d12 + 5) piercing damage, and the target must make a DC 16 Constitution save or suffer the effects of Wyrmblood Venom.

Claw

Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 25 (3d12 + 5) slashing damage.

Swarm

Melee Weapon Attack: +8 to hit, reach 0 ft., one creature in the swarm's space. Hit: 57 (8d12 + 5) piercing damage, or 31 (4d12 + 5) piercing damage if the bone collective has half its hit points or fewer. If the attack hits, the target must make a successful DC 15 Constitution save or suffer the effects of Wyrmblood Venom.

Wyrmblood Venom (Injury)

Bone collectives create a reddish liquid, which they smear on their fangs. The freakish red mouths on the tiny skeletons are disturbing, and the toxin is deadly. A bitten creature must succeed on a DC 15 Constitution saving throw or become poisoned and take 1d6 Charisma damage. A poisoned creature repeats the saving throw every four hours, taking another 1d6 Charisma damage for each failure, until it has made two consecutive successful saves or survived for 24 hours. If the creature survives, the effect ends and the creature can heal normally. Lost Charisma can be regained with a lesser restoration spell or comparable magic.