Very clever mechanic, I really liked it.
Initially it was very confusing though since I didn't quite get how the ribbon worked. My first assumption was that the colors on the left side applied to the left field, and the right side to the right field.
So that could perhaps be a bit more visually clear, to show the association.
maybe having :
x kills y
z kills w
instead of :
x,z kills y,w
But great job, was very fun.