In 2009, the Colorado-based duo Cobalt released their third LP, Gin — one of the 10 best metal albums of the last decade, as far as I’m concerned. The album came complete with a fascinating narrative: It paid tribute to Hunter S. Thompson and Ernest Hemingway — the cover image is a sepia-toned photo of a young Hemingway in his Army uniform — and it featured on vocals a singer named Phil McSorley, himself an active Army officer whose ability to write and record his tracks was limited by his tours in Iraq and South Korea. But the music was more fascinating still: Cobalt’s driving engine was (and remains) multi-instrumentalist Erik Wunder, who also works as Man’s Gin and has done time in Jarboe’s band (Jarboe added guest vocals on both Gin as well as Cobalt’s magnificent second LP, Eater Of Birds). McSorley was a black-metal lifer, while Wunder’s primary influences were Swans, Neurosis, and Tool, and that dynamic resulted in music of unparalleled scope and vision.

In 2013, with McSorley stationed in the States, Cobalt played their first-ever live shows — and prior to those shows, Wunder announced that Cobalt were working on a fourth LP, to be titled Slow Forever, a reference to the band’s glacially paced writing and recording process. But in 2014, it all fell apart: McSorley quit the band in March of that year, rejoined a month later, and then, in December, was kicked out for “spewing misogynist/homophobic slurs on Facebook to other musicians.”

But Wunder continued work on Slow Forever, and in June 2015, enlisted a new vocalist: Charlie Fell, who’d been kicked out of his own band, Lord Mantis, only three months prior. Politically, it was an odd choice: Fell has a history of bad behavior and dubious, insensitive artistic choices. There were additionally concerns about whether the album would be any good: Wunder was famously the mastermind behind Cobalt, but McSorley seemed to be an essential ingredient, and while Lord Mantis had made some very fine records, they’d never approached the Himalayan heights of Gin or Eater Of Birds. Those concerns were not mitigated by statements like this one from Cobalt’s label head, Chris Bruni from Profound Lore Records:

Out of its 86 minute running time, there's maybe about a minute of anything sounding remotely black metal on the new Cobalt album. If that.

— Profound Lore (@profound_lore) December 27, 2015

So when advances for Slow Forever rolled in, the first response (from this writer, anyway) was basically: Oh thank god this doesn’t suck. With that out of the way, real analysis could begin … and that sounded something like this: Oh my god, this is actually fucking awesome. And that’s where I stand today.

Slow Forever is very much an extension of Gin, an expansion of Wunder’s evolving vision. Fell is more than an adequate replacement for McSorley — in many ways, he’s a superior vocalist, and here, he delivers a performance that is more technically adept than those offered by his predecessor, but no less unhinged. Slow Forever isn’t just a worthy follow-up to Gin; it’s pretty close to a masterpiece in its own right. Bruni was right about the absence of black metal on this album, but then again, Cobalt were never a black metal band to begin with. They fused blackened death metal with noise, doom, crust punk, and post-metal, but never fit into any existing category. And with Slow Forever, they move further away from any previously settled terrain, further into their own sovereign territory. Today at NPR, Cobalt deliver Slow Forever’s first single, “Beast Whip,” which is a perfect introduction to the album. It’s layered, dark, beautiful, violent, and climactic. Listen.

Slow Forever is out 3/25 via Profound Lore.