This is meant to represent the most simple primary secondary common, using existing Magic mechanics.

I wanna give Deathtouch as the Black keyword and Trample as the Red/Green keyword, but those generally are never printed on the same card, and Green gets Deathtouch anyways. So howabout Lifelink?

Part of the struggle here is that Black does get Trample at sufficient creature size. Is there a more interesting keyword we can give this?

Black has some Beasts, but Red and Green have far more. Dinosaurs, too. Black brings the Nightmare.