Rage Against The Machine and Audioslave's Tom Morello will feature, too.
While the wait for new System Of A Down music continues (but there are reasons to be cautiously optimistic), drummer John Dolmayan has been working on another project of his own.
Speaking to System Of A Down Mexico, he revealed that he'll be releasing a record with his band These Grey Men within the next four months - and it'll feature guest appearances from SOAD frontman Serj Tankian, Avenged Sevenfold's M. Shadows, and Rage Against The Machine's Tom Morello.
"There’s some cool artists on it," he explained.
"Serj sang two songs. The Avenged Sevenfold singer... he sang a song, and then I have a bunch of other friends that came, Tom Morello played guitar on a song. I know it’s been forever, but it will be released.”