Rats

Characteristics

Disposable. The Rat takes double damage from effects and spells that deal damage based on a failed saving throw, and even if it succeeds on the saving throw, it takes full damage instead of only half.

Keen Smell. The Rat has advantage on Perception checks that rely on smell.

Pack Tactics. The Rat has advantage on an attack roll against a target if at least one of the Rat's allies is within 5 feet of that creature and the ally isn't Incapacitated.

Attacks

Bite. Melee Natural Weapon Attack, -1 to hit, 5 ft. reach, one target. On a hit, deals 1 (3d2-3) Piercing damage.

Characteristics

Collective. The Rat Swarm can enter and exit the space of a creature equal to or smaller than its own size; the space inside the Collective is considered difficult terrain, and the Collective has advantage on attack rolls against creatures inside it.

Split. The Rat Swarm can split into two Rat Swarms of 1 smaller size category using a bonus action, losing half its maximum and current hit points in the process, and its Bite attack's damage die is decreased by one category. A Rat Swarm can merge with another of the same size using a bonus action, adding their maximum hit points together and increasing its damage dice by one category. A Rat Swarm can't be smaller than Tiny. A Tiny Rat Swarm splits into 1d4 Rats.

Keen Smell. The Rat Swarm has advantage on Perception checks that rely on smell.

Pack Tactics. The Rat Swarm has advantage on an attack roll against a target if at least one of the Rat Swarm's allies is within 5 feet of that creature and the ally isn't Incapacitated.

Attacks

Bite. Melee Natural Weapon Attack, -1 to hit, 5 ft. reach, one target. On a hit, deals 7 (3d6-3) Piercing damage.