Photo by Nik ChristoffersonSlayer frontman Tom Ayala shreds dutifully at WaMu Theater.I honestly have no idea how many Slayer or Megadeth shows I’ve attended at this point in my life–probably more than half-a-dozen, perhaps less than twenty. Either way, they are collectively the mashed potatoes and gravy of metal for me: familiar, classic, comforting. I arrived just in time to hear the opening strains of Megadeth’s “Holy Wars…the Punishment Due,” and it sounded just as electrifying as it did when I first heard it in 1990. Hearing Rust in Peace in its entirety was a delight, even if the subsequent tracks from 2010’s Endgame left me listless. Dave Ellefson’s bassline signaled the start of closer “Peace Sells (But Who’s Buying)” and the audience went predictably apeshit. Slayer is Slayer. As far as I’m concerned, as long as drummer Dave Lombardo is in his rightful place behind the kit, nothing can really go wrong. This isn’t a critical copout: Slayer is a veritable machine of a band, and they’re pretty much always going to make young men (and the occasional woman) throw their shoes, scream incoherently, and thrust their hands skyward, devil horns thrown with pride. Focusing on Seasons of the Abyss was a wise choice, as was not forsaking the requisite title track from Reign in Blood and its accompanying go-to “hit,” “Angel of Death.” The only downer was the closure of the beer gardens during the start Slayer’s set. Even at $9-$10 a pop, being denied a beverage during the headliner’s set seems a tad anti-climactic.