I can’t count how many times I’ve seen Slayer on two hands. And they’re just as indescribably incredible live now as the first time I saw them a decade ago. They don’t change and they don’t fuck around. There’s never been a ballad or even a slight deviation from who they’ve always been. They are 100 percent Slayer. You can expect them to be every bit as brutal as ever. You should expect to be a little afraid of the Slayer fan next to you (he/she is not gonna stop headbanging or thrashing around for you or anybody). Expect to see a little blood and walk away with a nice souvenir bruise. With Exodus and Rob Zombie. (WaMu Theater, 800 Occidental Ave S, www.wamutheater.com, 7 pm, $45, all ages)