TORONTO - Halloween came early for Toronto hard rock fans last night, as horror-themed headbangers Slipknot pummelled the Air Canada Centre with 90 minutes of grotesque musical tricks.

The nine-piece Iowa group has built a pretty successful career on being creepy looking, always appearing in uniforms and individually customized, bizarre rubber masks that make Mike Myers' melting William Shatner face look tame by comparison.

Percussionist Shawn Crahan recently told MTV that their goal "is to be as completely uncomfortable as humanly possible for art." Their music is pretty nasty, too, what with song titles like Pulse of the Maggots and People = Shit.

Slipknot is like Marilyn Manson times nine and they've crafted a bad enough reputation that the venue had extra staff on hand just to confiscate studded belts from the kids before they could enter, lest the "devil's music" whip them into a chain-throwing frenzy.

(Frankly, an offensive, litigation panic-fuelled policy that seemed arbitrarily enforced; nobody asked me to remove mine.)

Of course, the band isn't really all that dangerous and the challenge last night was to bring the ferocity of their image and albums to a huge arena that was less than half full.

The Subliminal Verses tour, which also hit Toronto's International Centre earlier this year, relied on typical teen-rousing cliches, mostly lots of swearing.

Singer Corey Taylor actually found new uses for the F-word. Opening with their aforementioned take on the old "hell is other people" sentiment, the band had the general admission floor audience writhing like a seething pit of fists and feet.

The non-stop barrage of drums and guitars was hard to keep up with, perhaps even for the players, as it was unclear how much was live and how much was triggered by their full-time guy on samplers. Guitarist James Root broke his wrist last week and left the tour, but they haven't replaced him. Nobody seemed to notice or care. They were too busy watching the two percussionists and the turntablist run about the stage like circus clowns and play on the hydraulic drum kits.

Perhaps, the reason the band's most recent album, Vol. 3: The Subliminal Verses, has moved away from "nu-metal" has nothing to do with musical trends and more because turntablist Sid Wilson (the one who looks like Skeletor) would rather jump around on stage than actually play anything.

An hour into the show and the antics were wearing thin. (With exception of a spectacular drum solo from Joey Jordison, whose kit was raised and flipped upside town, a la Tommy Lee.) Then they pulled out a simple but effective manoeuvre to get the energy up: Asking everyone on the floor to crouch down, then at Corey's command, to jump like maniacs.

It worked, and the show peaked with Spit It Out before the more PG-rated hit Wait and Bleed.

Slipknot's brand of shock rock may not be the true terror they market it as, but on the eve of Halloween season, it was a pretty good treat.