I started checking for them as they were listed as having done some live instrumentation for Aesop Rock's last two albums, and Aes has remixed a few of their songs. They released a new EP on Rhymesayers which is nice.

They probably first came on my radar from Aes's remix of "Bosico", but the original which is completely different is my favorite track of theirs...I've listened to this so many times:

https://grimacefederation.bandcamp.com/track/bosico

and the title track from their RSE EP:

https://soundcloud.com/grimace-federation/1-grimace-federation-the-measure-in-mixture