When Mastodon's Leviathan, that rarely-matched-since slab of whale-sized sludgy goodness, came out in 2004, it looked like Relapse Records was on top of the metal world. The label's subsequent release of essential discs from the likes of Nile, Pig Destroyer, and Baroness seemed to solidify this status and prophesy a bright and glorious future for the old guard label. Then something happened. Mastodon left for Warner Brothers. Nile left for Nuclear Blast. Pig Destroyer stopped working. (Still in the studio for that new one, guys?) Baroness continued to rock, but became so popular so quickly that soon most of their fanbase didn't have a clue about Relapse Records, let alone its erstwhile triumphs. A new crop of bands came to the label – Howl, Black Tusk, Red Fang, et al – who oozed competency but rarely creativity. Labels like Profound Lore, Southern Lord, and Neurot had eclipsed the once mighty leviathan (pun intended) that was Relapse Records circa 2004.

Enter Tombs. The New York-based trio has been with Relapse since 2009 and already has three releases on the label under its belt, and while what they're doing isn't entirely novel, it's interesting enough to hint at a new Golden Age for Relapse. By fusing the swampy sludge of EyeHateGod, the slithering post-metal of latter-day Neurosis, and the black-metal-by-way-of-Tool fury of Cobalt, Tombs has carved out a corner of the metal genre that may not be completely new, but is occupied by few enough bands that their excellent execution lets them rise near its apex. Their latest album, Path of Totality, operates within that general framework without doing much to prod its edges. Where it finds success in spades is its overwhelming heaviness; there hasn't been an album this crushing since another sepulchral band, Japan's Coffins, dropped the immense Buried Death in 2008.

Crucially, Path of Totality's heaviness must not be equated with a lack of nuance. This is complex, serpentine music. It's built on riffs – as most great metal necessarily is – but it never uses them as a substitute for good songwriting or leans on any one as a crutch for too long. It's thanks to a superior mixing job by producer John Congleton that the album is allowed to sound so heavy without losing any of its integral intricacy. The production job allows Tombs to pummel away with their punishing wall-of-sound barrage while still allowing individual instruments to be picked out from the mix. It seems like every song has some passage where the guitar tracks should by all accounts be bleeding together into an indiscernible cacophony of tremolo picking and distortion, but they never do. Perhaps the least black metal thing about Tombs is that during their most black metal moments, the production remains clear – not neutered or sterile, but clear – enough to lend the music an air of professionalism that was absent from (and, indeed, highly contributory to the atmosphere of) the classic records from bands like Darkthrone and Burzum.

But great production alone can't make a great album, and guitarist/vocalist Mike Hill, bassist Carson James, and drummer Andrew Hernandez are the parties most responsible for Path of Totality's staying power. Their chemistry as a unit is evident throughout the album, especially in the chaotic ruckus of opener 'Black Hole of Summer', where no member overpowers another through five relentless minutes of pounding blackened sludge, as well as on album highlights 'To Cross the Land' and 'Cold Dark Eyes', where the band stretches their songs beyond the six minute mark without the music becoming dull for even a second. Hill's vocals on the album occupy that nebulous region somewhere between the across-an-ocean shouting of Isis' Aaron Turner and the throaty black metal howls of Watain's Erik Danielsson, and they suit the music behind them (or in front of them, really – as with so much extreme metal, the vocal tracks sit toward the back of the mix) beautifully.

Whether Tombs will burn out before they can reach their lofty potential or jump ship for another record label has yet to be determined, but for now, they're one of Relapse's potential saving graces. Path of Totality is an imperfect album – it's at times meandering and probably a few tracks too long – but it marks a resurgence nonetheless, both for its label and perhaps even its subgenre. With any luck, the new face of Relapse will be dominated by forward-thinking young acts like the excellent Black Anvil and Tombs. The sky, it seems, is their only limit.