Swarm. The swarm can occupy another creature's space and vice versa, and the swarm can move through any opening large enough for a Tiny raven. The swarm can't regain Hit Points or gain Temporary Hit Points.
Beaks. Melee Attack Roll: +4, reach 5 ft. Hit: 5 (1d6 + 2) Piercing damage, or 2 (1d4) Piercing damage if the swarm is Bloodied.
Cacophony (Recharge 6). Wisdom Saving Throw: DC 10, one creature in the swarm's space. Failure: The target has the Deafened condition until the start of the swarm's next turn. While Deafened, the target also has Disadvantage on ability checks and attack rolls.