Flask of Battle

The Flask of Battle was introduced in the World of Warcraft: Cataclysm expansion as a guild reward for alchemists.

Source
They're obtained by use of either a Cauldron of Battle or Big Cauldron of Battle. When used, it grants the effects of a flask that's based on your class and talents. The base duration of this buff is one hour, but this is increased by the guild perk Chug-A-Lug, increasing to 90 minutes at guild level 10, and 2 hours at guild level 22.