It was puzzling. Heart had already played every major hit that could

It was puzzling. Heart had already played every major hit that could come to mind. And yet, sitting in a darkened Key Arena, the fans who filled the lower bowl stomping and clapping, knowing from the Bumbershoot schedule that the band had 20 more minutes, at least, it was clear that there would be an encore. But what would the band play?

Led by sisters Ann and Nancy Wilson, the band had spent the previous hour pummeling the audience at Key Arena with a reminder, not only of the band’s greatness, but of the power of well-crafted arena rock. In a cavernous space that has trouble with bass-heavy hip-hop and thin indie pop, the over-the-top balladry and chugging rhythms of this band sounded not only good, but at home.

“Barracuda” opened with backlit Nancy striking a menacing guitar goddess pose. Before the end of the song, she unleashed a torrent of sound during a swerving atonal solo, expertly holding her Gibson like a mighty rock ‘n’ roll phallus, the incongruousness reminding that, yes, she is a woman, the expert playing reminding anyone dumb enough to think otherwise that, no, that doesn’t matter. Ann was equally on point, her acrobatic vocals rarely failing to hit the peeks of four decades hence. When they did falter, it was a reminder that she is human, though given the emotional heft of the band’s catalog, that fact isn’t really in dispute.

The band played on. “Heartless” from the 1977 LP Magazine followed. 1985 mega-hit “What About Love,” with its synthy spine, shifted the band quickly from its rock roots to its big-hair hey day and revealed Ann, through her tortured expressions and clenched open fists, as a potential model for Jack Black’s satirical turn in the mock band Tenacious D. The classic “Magic Man,” off the band’s debut Dreamboat Annie followed, and the hits, as they say, just kept coming. “Kick It Out,” “Mistral Wind,” “Even It Up,” “Dog and Butterfly.”

Nancy broke from the parade to dedicate a solo acoustic version of Elton John’s “I Need You to Turn” to the city of Seattle. It was a bit of a snooze, the performance endearing, but the relatively thin vocal lost in the room. No matter, the band returned to stage and filled it up again, playing back-to-back power ballads “These Dreams” and “Alone.”

Then the band played its only contemporary song, “Dear Old America,” from the 2012 album Fanatic. Ann introduced the song as a piece of music inspired by her veteran father, her voice breaking some when she described the repercussions of war on her dad. “It was hard, hard, hard,” she said before falling stars and stained stripes appeared on the screen behind her as her sister played the song’s intro, a warped reimagining to the national anthem. Of all the artists I saw today at Bumbershoot, in a moment where our country is again contemplating yet another war, this was the only performance that even acknowledged the subject, though in a general sense. “When I get home I’m gonna shove my doubts,” Ann sang in the voice of her father. “Dream my dreams and shut my mouth. Nobody knows what this is all about.”

For Heart’s 13th and final song, Pearl Jam guitarist Mike McCready joined the band and, following a ornate acoustic intro by Nancy, tore into the unmistakable descending riff that undergirds “Crazy on You,” the band’s breakout single from 1976. It was a scorching rendition, a perfect end to the set. Where to go from there? And what else left to play?

The answer came as the lights came up and revealed a second drum kit on stage, that belonging to Jason Bonham, son of original Led Zeppelin drummer John Bonham and leader of the Led Zeppelin Experience, which has been touring with Heart and packed the arena early in the night. There would be no more Heart. Instead the band played a six-song all-Zeppelin cover set for its encore.

The sisters opened with a duet on “The Battle of Evermore” from Led Zeppelin IV. After that the full band, plus Bonham, took the stage and played “Misty Mountain Hop,” “Immigrant Song,” “The Rain Song,” “Kashmir,” and, finally, obviously, “Stairway to Heaven,” which opened with Nancy playing the acoustic intro. As Ann started in on the vocal, Seattle’s Total Experience Gospel Choir, which early played the Starbucks Stage, shuffled in behind the band. As the song picked up, the choir joined in with “Ah-ah-ah”s, finally joining in the vocal as Ann sang, “Your stairway lies on the whisperin’ wind.” The band took over from there playing the song into its dazzling climax before dropping out and handing it over to Ann. The singer milked the moment, briefly, and then ended the two-hour concert. “And she’s buy-uy-ing a stair-air-way … to heh-vun.” The choir hit that last syllable with her. It was epic.