Critter

Keen Smell. The rat has advantage on Wisdom (Perception) checks that rely on smell.

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

Bite. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 4 (1d4 + 2) piercing damage.

Poisoned Barb. Ranged Attack. +5 to hit. Range: 5-30 ft. Hit: 4 (1d6) poison damage. Target must make a DC 13 Constitution save or be paralyzed until the Critter's next turn.

Roll. The Critter curls into a ball and can make a Dash movement. Attacks of opportunity against this at disadvantage.