Ferrafor, Young Yew

The tap ability is the tell: this is a counters-payoff commander dressed as a Saproling generator, and the two halves are wired to feed each other. The enters trigger reads any counters among a player's creatures and pays out in bodies, which invites a build stuffed with +1/+1 counters, keyword counters, charge counters, anything the game can stack. Then the activated ability doubles every kind of counter on a single creature, not just power-boosters: a creature holding a lone loyalty-style or oil or level counter walks away with two, and the doubling stacks across turns since it can be pointed at the same target repeatedly. Green has flirted with counter-doubling before (Doubling Season sits at the color's structural center), but folding that engine onto a body with a token payoff attached, and letting it target creatures you do not control, changes the math from a persistent enchantment into a repeatable, aimable effect. The 4/7 frame is defensive on purpose: this is a card that wants to survive to untap, not swing, and the toughness buys the turns the doubling needs to snowball. What makes it more than a durdle is the loop it implies. Double a creature's counters, remove and replay Ferrafor, and the enters count balloons; the two abilities are not two effects sharing a card so much as two ends of the same growth curve.