Last year, Doom Eternal composer Mick Gordon put out an open call for vocalists to join a heavy metal choir for an unspecified project. That unspecified project was, not surprisingly, Doom Eternal, and more than 20 vocalists teamed up to create a creepy chant that crops up throughout the soundtrack.

A new video goes behind the scenes of the soundtrack's creation, showing us some heavy metal choir practice and interviews. It's a pretty big genre, and it looks like Gordon's put together an eclectic mix of musicians that reflects that.

Wildspeaker vocalist Natalie Kahan points out that the choir has an equal gender split, and there's variety when it comes to their singing style, too. The choir even features some Mongolian throat singing, courtesy of Tengger Cavalry's Nature Ganganbaigal, who unfortunately passed away last year.

The chant itself is "pieced together from a mysterious and ancient language that harkens back to the Slayer’s origins" and it's woven into the rest of the soundtrack. You can get a proper taste of it at the end of the video, which should get you pumped enough to slaughter an army of demons.

Here's the list of performers:

You'll be able to treat your ears when Doom Eternal launches on March 20.