Upon seeing Dengar crush a Kenku with a single blow, Erdan spots one of the other bird people looking Dengar's way and lets an arrow fly towards them.

Spoiler: Attack roll and damage
Show
Attack roll with advantage since stealth on roof

(1d20+5)[21]

(1d20+5)[13]

Damage + sneak attack damage since hidden and first attack.

(1d6+3)[7]+(1d6)[1]