So, Cold Dark Place is actually a thing! Back, when Mastodon were writing Emperor of Sand, there was talk about a double album, with the second half being written entirely by Brent Hinds. That obviously didn't happen, as EoS ended up being a single record. Then, in the best interview ever made (check it out below), Brent said an album called "Cold Dark Place" will be released "on Record Store Day in June". The record is supposedly about a "nasty breakup". Brent described it as "pretty dark, beautiful, spooky, funky, ethereal, melancholy music, which also sounds like the Bee Gees a little bit." No word on if it will be a full album or an EP, but it's definitely coming.
Should be released together with Emperor of Sand, not a big deal alone as a ep.