The unique gromril flask is adorned with jewels and trimmed with filigree. There are a few words etched into the metal on the flask that read: Care of MB, esquire.
Tome Unlock: Pick up a Rare Flask in the Redhammer Brewery in Dwarf Chapter 2, and use the flask from your inventory. It's on the left of the fireplace.
This tome unlock contributes to the The Mysterious M.B. pursuit.