Buzz Osborne and Dale Crover, the core of the Melvins for more than 20 years now, run their band like a Mongol horde--sweep down on your enemies from both flanks at once, change tactics constantly, and know when to kill everything in your path and when to settle down and impregnate a few locals. (It's amazing how many bands have a little Melvins DNA in them somewhere--figuratively speaking, of course.) In the past couple years they've collaborated with Jello Biafra and dark-industrial pioneer Lustmord, and last spring they released A Live History of Gluttony and Lust (Ipecac), a blistering revision of their 1993 Atlantic album Houdini with Trevor Dunn on bass. Recorded this summer and forthcoming next month is (A) Senile Animal, a spectacular curveball: ordinarily a trio (with one of about a zillion different bassists), the Melvins have become a quartet, absorbing both members of the pummeling bass-and-drums duo Big Business. Yep, two drummers--Crover's a righty, Coady Willis of Big Business a lefty, and word from Dale is that they'll be sharing his big toms between them, moving like mirror images of each other on the unison parts. No band with Crover in it can be said to need a second drummer, but Willis isn't just gilding the lily--the seismic rattling and thundering beneath Buzzo's sinister slabs of rubbery riffage sounds like the hoofbeats of a dread army pouring over the hill. Big Business and Ghostigital open. a 9 PM, Double Door, 1572 N. Milwaukee, 773-489-3160 or 312-559-1212, $17.50.