Narnam Cobra

A 2/1 body that converts into a combat wall the moment one green mana comes available, with a colorless artifact frame that keeps it eligible for affinity and metalcraft-style payoffs. The deathtouch is repeatable and instant-speed, so the snake answers anything in combat: hold up the green and it trades up against giants, dragons, and anything else that walks into it on either side of the board. The activation cost is what disciplines the rate: each green you spend buys deathtouch for one turn only, so there is no permanent threat, no banked value. You have to actually have the mana open when the block matters, which turns the card into a recurring tax on your green sources rather than a passive deterrent. Where it earns its second look is the type line: a colorless artifact creature whose only meaningful ability wants a green source, it sits in the seam between an artifact-matters deck and a green creature deck without committing fully to either. That combination of a metalcraft-relevant body and a green-pip activation is the tension the design resolves, asking the artifact deck for a splash and asking the green deck to count it among its artifacts.