Quipper, Swarm of Quippers

Blood Frenzy. The swarm has advantage on melee attack rolls against any creature that doesn't have all its HP.

Heightened Smell. The swarm's Perception is 15 when perceiving by smell.

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 quipper. The swarm can't regain HP or gain temporary HP.

Swarm Resilience. The swarm is resistant to bludgeoning, piercing, and slashing damage, and it is immune to the charmed, frightened, grappled, paralyzed, petrified, prone, restrained, and stunned conditions.

Water Breathing. The swarm can breathe only underwater.

Bites. _Melee Weapon Attack:_ +5 to hit, reach 0 ft., one creature in the swarm's space. _Hit:_ 18 (4d8) piercing damage, or 9 (2d8) piercing damage if the swarm has half of its HP or fewer, and the target must succeed on a DC 13 DEX save or have its flesh shredded by the attack. A creature with shredded flesh loses 4 (1d8) HP at the start of each of its turns as the wound bleeds profusely. Any creature can take an action to stanch the wound with a successful DC 10 WIS (Medicine) check. The wound also closes if the target receives magical healing.