Deafening Clatter. Creatures are deafened while in the swarm's space.
Swarm. The swarm can occupy another creature's space and vice versa, and the swarm can move through any opening large enough for a Small humanoid. The swarm can't regain hit points or gain temporary hit points.
Slash. Melee Weapon Attack: +4 to hit, reach 0 ft., one target in the swarm's space. Hit:11 (2d8 + 2) slashing damage, or 6 (1d8 + 2) slashing damage if the swarm has half of its hit points or fewer.
This swarm of bones found rising out of the sand in Isle of the Abbey is made from the remains of several animated skeletons. A skeletal swarm alternates its appearance between partially formed humanoid shapes and a chaotic, swirling mass.