It's one of heavy metal's most signature sounds, sonorous and operatic, a summation of the genre's defining principle: Too much is never enough.

Pair Dio with two of his former Black Sabbath running mates -- guitarist Tony Iommi and bassist Geezer Butler -- along with veteran drummer Vinny Appice, and you get Heaven and Hell, a band so metal, it deserves its own spot on the periodic table of elements.

Touring together for the first time in 15 years, the guys hit The Pearl at the Palms on Friday night like an anvil dropped from a second-story window.

When Dio replaced Ozzy Osbourne as Black Sabbath's frontman in 1979, the band underwent an instant metamorphosis: The tunes became much more elaborate and adventurous, with long thesis statements on epic metal songcraft and Iommi and Butler going for it like a couple of pit bulls that have chewed themselves free of their leashes.

The Dio era will never match Ozzy's tenure in the band in terms of influence, but the two discs that Dio cut with Sabbath -- along with an underrated 1992 comeback album, "Dehumanizer" -- contain some of the group's most multifaceted and overlooked moments and capture the band members at the peak of their capacities in terms of a confident, complex musicianship.

Heaven and Hell basically has two types of songs: sweaty, hard-charging rockers, and doleful, atmospheric dirges that eventually turn into sweaty, hard-charging rockers.

At The Pearl, the band alternated between the two from song to song, opening the show with full-throttle grinder "Mob Rules" before segueing into the mournful "Children of the Sea," a grandiose, boulder-dense number that begins with a flickering of Dio's voice and ends with a cascading wall of power chords.

Iommi, in particular, was in vintage form through it all, soloing for days, displaying a whole other side to himself as a guitarist.

In Sabbath's first configuration, Iommi focused almost solely on the riff -- huge and elephantine, dark and downtuned -- for which he's known as a metal pioneer.

But with Dio in the lineup, Iommi displayed a new sense of showmanship and vigor, with much longer, more involved and brighter solos alive with sprightly, bluesy licks.

On stage, Iommi's a stoic and lumbering presence, as if his limbs were carved from wood.

But his playing is anything but, fluid and fleet, with an emphasis on velocity and fretboard gymnastics.

With Iommi in charge, hard- grooving rocker "Voodoo" became a 15-minute buffet of shape-shifting rhythms topped off by a drum solo in which Appice hit his kit so hard, it swayed like a sapling caught in a violent thunderstorm.

The band's signature "Heaven and Hell" underwent a similar treatment, fleshed out into a monolith of sun-swallowing guitars and domineering basslines.

It was all enough to get plenty of Bics in the air from a crowd of headbanging dads and kids in death metal T-shirts.

This was metal's past reasserting itself in the present with deliberate force, and for one night, Hell wasn't such a bad place to be.

Contact Jason Bracelin at jbracelin@reviewjournal.com or (702) 383-0476.