It was billed as a battle, though the only true confrontation at The Roots vs. Antibalas Sound Clash throwdown was in the audience’s pummeled minds.

Everyone anticipated the ridiculousness of the Red Bull-sponsored one-of-a-kind event, the $15 bargain tickets were going for $100 on Craigslist, and the surprise factor of how it would go down only kicked the hype up another level. We marched up the stairs into the swank Roxy, took our positions on the wooden ballroom floor corralled between two stages and a DJ booth, and accepted our fate.

The host for the evening, Boston MC and Mr. Lif partner “A to the Muthafuckin K” Akrobatik, announced the rules of the match from his balcony tower. It would go back-and-forth between bands through different styles, rounds and challenges, like an acid-test game show without the embarrassingly sleazy, womanizing host.

Led by front line New Orleans-style sousaphone maniac Tuba Gooding Jr.’s relentless bouncing across the stage, the Roots launched the first salvo of the night. Never attempting to replicate the cut-and-dry boom bap of vinyl, which too many live hip-hop acts try and fail to do, the crew keeps the essential live sound legit and smooth. A few excursions into Sabbath’s “Iron Man” and the classic “Apache” jam got the hands in the air.

As the Antibalas Afrobeat Orchestra took over and spun the crowd around, the Roots remained on stage and nodded with the rest of us. Antibalas would do the same during the Black Thought/?uestlove machine’s turn. No one was missing out on this.

Though the style collision between urgent Philly soul and laid-back Brooklyn hipster was almost comical, the juxtaposition of hip-hop and afrobeat made for the perfect mix tape. The musicological statement of pitting two wildly different genres against each other, while recognizing both trunks feed from the thick roots of James Brown, was bold and unifying.

A round of covers saw each band adapting TV themes from “Cheers,” “The Jeffersons” and “Knight Rider.” In round two they started originals and asked the other to finish up. After the Roots dropped “Star,” Antibalas blasted a trombone-led horn fanfare version of the melody. Then Antibalas erupted with “Pay Back Africa,” their opponents somehow morphing the ululating dirge into a poppin track of their own.

The natural tendency of successive bands on a bill to show each other up was annihilated with the Sound Clash format. Instead, the ping-pong parameters continually twisted the intensity tighter as each group fed off the other.

DJ Kon led round three by spinning quick samples of hot tracks as inspiration for remixes. Antibalas’ dubbed-out response to Sister Nancy’s “Bam Bam” was particularly tasty, though its swing version of “Who is this America?” faltered (though props for Chris Vatalaro’s confident Buddy Rich flailing drum solo ending). The Roots also found difficulty in the jazz realm, though the hand-clapping gospel mashup of “The Next Movement” killed.

The zeal spawned by the Sound Clash opportunity was evident in both bands. Though it may have been presented as spontaneous, the amount of writing, rehearsing and preparation required to pull off the show was impressive. To devote that work to a one-off gig is testament to the artists’ integrity, vision and passion.

The finale of the night featured each band with special guests. Antibalas brought in Rich Medina, a Philly DJ who incorporates afrobeat in his repertoire, for a spoken word session. The Legendary Roots Crew pulled on stage alto sax legend Gary Bartz, a member of the Miles Davis fusion band recorded on the classic Live/Evil album, for a spicy rendition of his “Celestial Blues.”

But the real highlight of the evening converged through Antibalas’ power grab. The late Fela Kuti’s afrobeat draws its monstrosity from its devotion to justice in this asshole-crowded world, not just its militant horn lines and irresistible, stomping groove. Antibalas stays true to this tradition and equally prospers from its synergistic alchemy. Notably, it was the group’s first show since the election of Barack Obama.

“Justice just got a whole lot sexier in 2009,” screamed face-painted frontman Amayo before cutting down the crowd with “Indictment,” the conflict-free-diamond-tipped chainsaw banger. “The bad guys are not forgotten.” Amayo reminisced about the tragic 2004 Boston Antibalas show at the Middle East on election night intended to be a victory party. I tearfully looked back at that evening and saw myself passed out on a bench by the pisser impaired by cheap beer and hopelessness.

With those thoughts, the Sound Clash quickly became vengeance: serious MacArthur-returns shit. The two bands finished together on one stage, appropriately thrashing through Fela’s “Beasts of No Nation.” Oh, and then a silky version of the Doobie Brothers’ “What a Fool Believes” to giggle about on the way out.