Description Black Flag Imperial Stout, the first beer released by Beer Valley Brewing, is a monstrously huge beer brewed for beer enthusiasts who want to test the edge of sensory perception. Brewed with 8 different malts and 4 different hop varieties to give it depth and complexity, Black Flag Imperial Stout delivers an extreme beer drinking experience like no other beer on the planet. Alcohol 11% alcohol by volume Hop Bitterness/IBU 100+ Seasonal.