Nass can be found hanging around the eastern room before the entrance to the Worg Pens. She was part of the raid on Waukeen's Rest, and was injured by a Flaming Fist soldier and is now tending to her wounds. If Minthara learns of the Emerald Grove's location and attacks it, Nass will take part in the attack.
Your attack summons thorny vines that possibly Ensnare your target.
Ensnared creatures cannot move and take 1d6Piercing damage at the start of each turn. An ally can use their Help action to try and tear away the vines.