Surge Conductor

Proliferate has historically been a payoff you pay for once, stapled to a spell you cast at your leisure: Contagion Engine, Karn's Bastion, the odd instant. The wrinkle here is that it fires on a trigger you're already generating for other reasons. If your deck is doing what an artifact deck does (churning out nontoken artifacts turn after turn), every one of those permanents becomes a proliferate on entry, no additional mana, no additional cards, no activation. That reframes what proliferate is worth. A single counter-adding effect is a repeatable engine when the fuel is your own gameplan; a +1/+1 counter theme, a planeswalker board, an infect kill, a charge-counter loop on some other artifact all compound with each new drop. The cost of that engine is written into the body: a 3/2 that does not survive much, and the trigger only cares about nontoken artifacts, so the token-swarm builds that most easily flood the board get nothing from it. It wants a specific kind of deck, the one already committed to real artifacts hitting the table one after another, and it turns that commitment into free counter growth. The design lesson is quieter than it looks: proliferate stops being a spell you tax yourself to run and becomes a rider on decisions you were making anyway.