Ezuri's Brigade

The conditional is the entire negotiation: pay four mana for a 4/4 that does nothing exceptional, or assemble three artifacts and watch the same body balloon into an 8/8 trampler. That swing is large enough to function as a payoff rather than a bonus, which is the design intent: metalcraft cards exist to reward an artifact density that green normally has no reason to build, and this one offers the steepest reward green got in the keyword's run. Most metalcraft creatures sweetened a small effect or added a counter; few doubled their printed stats and bolted on trample, turning a fair midrange threat into a clock that demands an immediate answer. The friction is that green is the color least equipped to hit the artifact count on its own. The card is a contract written for an artifact-forward green deck that has already committed to the count, and it punishes you with a vanilla body the moment your board of artifacts thins below the threshold. Trample is the load-bearing rider: an 8/8 that gets chump-blocked is just a 4/4 with extra steps, but trample makes the metalcraft state lethal even into a clogged board, which is exactly when an artifact-heavy deck wants to be turning sideways.