Quench is a somewhat playable counterspell, mainly in Standard
Skullclamp is also perfect for green because you tend to run a multitude of 1-toughness critters that will draw you two cards per equip
Hofri Ghostforge At first glance, Hofri might seem like a Spirit typal commander, but thats where youre wrong, because Hofri turns creatures that die into Spirits, you can make him the commander of any number of typal decks
Underrated EDH Card #33: Path of Mettle ($0.49) For lots of Boros decks it's trivial to flip this, by running good cards (Sun Titan) and good anthems (Anger)
What to watch: if cheaper exile or bounce tools become common, Cobras role shifts from main-deck staple to sidegradebut it will still move as a safe pickup
It also feels, to me at least, like it would be easy to upgrade into something pretty over-powered with the right additions