GATHERED FOR WORSHIP: Three bands serving the riff.

First up was Priestbird (formerly Tarantula A.D.), a New York trio that achieved their orthodox tectonic grooves with some decidedly unorthodox instruments, including a ten-stringed, double-necked guitar-bass hybrid and a bizarrely amplified and distorted cello. Their stoned, neo-Sabbath stomp was punctuated by explosions of thrumming doom, but the band was also comfortable at lower volumes, intertwining haunting cello dirges and noodly guitar psychedelia to create an eerie reverie.

The Boston-based buzz-saw of Clouds shattered this meditative mood. Propelled by the searing leads of Cave In guitarist Adam McGrath, Clouds fused the frenzy of hardcore with the bluesy fretboard squeals that result from the collision of classic, southern, and stoner rock. The tunes walked a tightrope between dissonance and catchiness, racing out of the starting gate with a fiery lick before happily collapsing into pummeling half-time. Barnburner “New Amnesia” was the highpoint of the set; after jokingly “forgetting” what comes after the first ten notes (get it?), Clouds reved into a rollicking guitar rave-up, with three-man caterwauls of “It’s a new amnesia” overlaying McGrath’s boogying, infectious guitar hook.

Chicago riff titans Pelican closed out the show, and justified the audience’s interest in their performance by providing vast swathes of their massive, monolithic heaviness. Anchored by the ten-ton rhythm section fraternity of Bryan and Larry Herweg, the band churned through a broadside of instrumental rock, shifting between bludgeoning quarter-notes and stately, tranquil grooves. The band’s compositional approach is one of meticulous tension-and-release and the deliberate construction and deconstruction of earthshaking walls of sound. Guitarists Trevor de Brauw and Laurent Schroeder-Lebec concatenated glistening reverb-laden indie leads, droning de-tuned chords, and squalling, ambient wankery, patiently accruing the strata of Pelican’s layered instrumental epics into rumbling crescendos, and then eroding them away. After the band’s triumphal encore, the faithful staggered into the street, liturgy concluded. We went in peace, to love and serve the riff.