This loop turns a simple sacrifice outlet into an engine of endless rebirth, all by reshaping the very nature of your creatures with Darkest Hour. Because every creature is painted black, every sacrifice fed to Carrion Feeder triggers Teysa, Orzhov Scion to immediately replace the fallen ally with a fresh 1/1 white Spirit token. That newly created Spirit is also made black by Darkest Hour, meaning it can be immediately sacrificed right back into Carrion Feeder to fuel the loop again and again.