If the party talks to him in the camp, he can be witnessed throwing a bone into the Shadow Curse and watching with glee as one of the Hyena's is killed fetching it. The party can elect to use their Illithid powers to command Gronag to go and fetch the bone instead.
If Gronag survives the trip to Moonrise Towers, or is never encountered, he can be found in Moonrise Towers in the room west of the throne room alongside Vez and Lora.
Normal weapon damage + Superiority DieWeapon damage
Spend a superiority die to deal Weapon Damage + 1d8 Physical damage and potentially force the target to drop the weapons they are holding.