Basically, it turns any block it touches a random color with a chance of giving it a random FX color. Then those block gradually turn the blocks they are touching again a random color with a chance of FX. Then blocks randomly start to break that are infected with it. Any player that touches it dies, any bot that touches it becomes a zombie, and any vehicle that touches it explodes.
This would be similar to the older mod that had those spreading bricks, but I feel some of the components of this would make it fun in different ways.