It's already a big day for beer geeks, but Surly's Darkness Day is also turning into an event of note for Twin Cities metalheads. This year's pre-Halloween tribute to the demonic brand of Russian Imperial Stout, happening Saturday at the Brooklyn Center brewery, will feature two semi-rare performances by locally reared metal bands: Powermad and Wolvhammer.

The former may not ring any bells to younger fans, but Powermad was argubaly the most thriving and hard-driving thrash band of the TC metal/punk scene in the late-'80s. It recorded an album and an EP for Warner Bros. and was a mainstay at First Ave, Ryan's and other venues. It also just so happen to feature a guitarist named Todd Haug, the man who would grow up and grow even more hair to become Surly's brewmaster. Haug, singer/guitarist Joel DuBay and bassist Jeff Litke recently put the old band back together, and they even have a new EP coming out. Hear the new single off it here.

Minneapolis-reared black metal quartet Wolvhammer has been kicking up an underground/blogger buzz the past couple years, in which time the band put out a pair of well-received albums on different labels but also splintered geographically to Chicago and San Francisco. Thus, it plays here less and less frequently. The guys recently toured with pioneering doom band Saint Vitus and are currently out with Chicago's Doomsday and New Jersey's Krieg, all of whom will also be playing together Friday at the Hexagon Bar.

As always, the rules for the beer portion of Darkness Day go like this: The first 800 fans in line Saturday morning – they might've started lining up already – will each be given a wristband starting at noon good for up to six of the $18 wine-bottle-sized bottles of the dark potion. They usually sell out soon thereafter. The party continues from noon to 6 p.m. outside the brewery. Surly's newest brew, the Brett Liquor IPA, will debut at the event. Click here for more details.