Received from Merrill if you don't turn him and his crew in to Louis for being drunkards. Merrill tells you of Louis' storage (the cellar door on the side of the church by the graveyard, which will now be unlocked). You can tell Louis that Merrill has been disloyal before entering but that will fail the quest. Instead, loot the storage finding a particular "Power Belt" which completes the quest for 450 exp or some gold. You actually still have the option of turning in Merrill and his buddies for being disloyal at which point he sends them all on a dangerous mission as punishment. You will run into them on this dangerous mission near Lovis' Tower, where they are all killed in front of you by a giant troll, as you watch helplessly. You gain no experience or loot from the incident, so just don't be a tattletale unless you just want to watch them all die.
The Power Belt can potentailly give infinite exp or gold if sold and bought back But only if you don't turn in merrill and his buddies -Worked in divinty II Ego Draconis- Recommend saving before tryng
Note: It is possible to still get the quest after you turn them in at the end of the Band of Brutes, if when you see them fighting the giant troll you talk to Merrill before he dies. The cellar door will become unlocked, and you can turn them in again to Louis. However, the Quest will never be considered completed in the Quest Log.