Who will go down in rock history as the best band to emerge from the late-1990s commercial heavy-metal boom? Korn deserve consideration for being first to the party, as do Limp Bizkit for selling more albums than anyone else on the scene. But the unsung heroes of the new-metal generation are Deftones, the long-running Sacramento act who rank as the genre’s most engaging stylists. With the new Deftones (Maverick/Warner Bros.), their first album in three years and fourth overall, and an opening slot on this summer’s Metallica tour, which stops by Gillette Stadium in Foxboro on July 6, the band are making a bold return to the spotlight at a time when many of their contemporaries are struggling to stay relevant.

The first single from the new Deftones album, " Minerva, " is one of the most challenging songs to hit rock radio this year. Like all of the band’s best work, it thrives on the tension between introspective frontman Chino Moreno and metalhead guitarist Stephen Carpenter. On the track’s uplifting chorus, Carpenter unleashes a swirl of crushing melodies while Moreno puts on his most passionate croon: " God bless you all for the song you saved us/For the hearts you break every time you moan. " Working with long-time producer Terry Date, the group achieve a powerful combination of beauty and dissonance.

Moreno and Carpenter formed Deftones in 1988, when they were both still in high school. With bassist Chi Cheng and drummer Abe Cunningham aboard, they released their major-label debut, Adrenaline, in 1995. Along with Korn, they were one of the few young metal bands of the era to make headway in the alternative-rock world. On their next two discs, Around the Fur and White Pony (all on Maverick/Warner Bros.), they let their ethereal side take over while new metal exploded all around them. The group earned their first platinum album and a Grammy for White Pony, but their sales numbers still paled in comparison with the legions of more accessible bands — like current tourmates Limp Bizkit and Linkin Park — who emerged in their wake.

There’s an age-old reason that Deftones’ commercial track record doesn’t live up to their reputation: they make albums, not singles. Mosh anthems and ambient dreamscapes co-exist in harmony on the new disc, which pledges allegiance to metal but refuses to heed any of the genre’s traditional constraints. Moreno and Carpenter have rarely sounded so in synch: the frontman emits a bloodcurdling scream whenever his guitarist kicks into overdrive, and the guitarist breaks into a Sonic Youth/Smashing Pumpkins melodic drone whenever his frontman gets mellow.

The group’s headbanging side wins out on the opening " Hexagram, " a violent reverie that probably has every fledgling screamo band in the country running back to the woodshed. " Play and worship, " screams Moreno in a fit of delirium while Carpenter’s guitar goes from a descending flutter to a vicious swipe. On " Needles and Pins, " Moreno makes a sacred pact with his lover and can’t stop screaming in celebration: " Who wants to fuck with us now? " He reaches new levels of abstraction throughout the disc, but he knows when to keep things simple for maximum impact.

Moreno turns to gallows humor on the ominous " Deathblow, " which tones down the guitar in favor of a swampy harmonica hook. On " When Girls Telephone Boys, " he latches onto the album’s grimiest groove and decides not to call her back: " Something’s wrong with you/And I hope we never meet again. " The rhythm section breaks into a relentless gallop that swings like vintage Pantera, and Carpenter’s noisy interjections terrorize the track. Moreno is determined to fall off the earth on " Bloody Cape, " and the band send him over the edge with a classic funk-metal tantrum.

The disc gets spacy at the end: on " Lucky You, " Moreno and turntablist Frank Delgado, who joined the band before White Pony, recruit special guests DJ Crook and Rey Osburn for a twitchy Depeche Mode homage. Delgado takes a seat at the piano on " Anniversary of an Uninteresting Event, " a pretty lullaby that finds Moreno at his most melancholy: " High on the waves you make for us/But not since you left have the waves come. " Sandwiched between " Bloody Cape " and the album’s lurching closer, " Moana, " the song is an apt showcase for the group’s impressive range. It’s also a good example of the dark, single-minded vision that’s keeping Deftones in the limelight.

Deftones open for Metallica on Sunday July 6 at Gillette Stadium in Foxboro; call (508) 543-8200.