Last year, "Doom Eternal" composer Mick Gordon solicited 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 the eerie chant that appears throughout the soundtrack.

A new video goes behind the scenes of the soundtrack's production, showcasing heavy metal choral exercises and interviews. Heavy metal is a fairly large genre, and Gordon seems to have assembled a diverse group of musicians that reflects this.

Natalie Kahan, vocalist for Wiles Speaker, notes that the choir has an even gender ratio and a wide variety of singing styles. The choir also performs Mongolian throat singing by Tengger Cavalry's Nature Gangambaigal, who unfortunately passed away last year.

The chant itself is woven into the rest of the soundtrack, "piecing together a mysterious ancient language reminiscent of Slayer origins." At the end of the video, you get a decent taste of it, and should be fired up enough to slaughter the legions of demons.

Here's the full list of performers:

Doom Eternal will be a treat for your ears when it comes out on March 20.