Buzz the Fly

Evasion: A housefly can avoid even magical and unusual attacks with great agility. When the fly is subjected to an effect that allows you to make a DEX saving throw to take only half damage, you instead take no damage if you succeed on the saving throw, and only half damage if you fail

Insect Climb. The fly can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.

Keen Sight and Smell. The fly has advantage on Wisdom (Perception) checks that rely on sight and smell.

Sense of smell. The fly can sense the direction and nature of any strong odor in up to 6 miles . This feature doesn’t reveal the location or any other information.

Annoying Buzz: When the fly occupies the same square as another creature, it buzzes incessantly. The target must make a DC 16 Wisdom saving throw, or its loose concentration on the current task. On a failed save, the creature has disadvantage until the end of your next turn. This ability does not work during combat.