Keen Hearing and Smell. Wren has advantage on Wisdom (Perception) checks that rely on hearing or smell.

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

Stalk and Leap. Wren can spend a turn not attacking to get a natural critical hit on an attack

Adorable. When a creature first sees Wren, they must succeed on a DC 10 Charisma saving throw or be charmed by Wren

Bite. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 7 (2d4 + 2) piercing damage. If the target is a creature, it must succeed on a DC 11 Strength saving throw or be knocked prone.

Scratch. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 7 (1d6 + 2) piercing damage.