Fallowsage

The trigger is the whole design problem solved in reverse: most card-draw engines ask you to spend mana or sacrifice something, but this one asks only that you tap it, which is a thing an aggressive board is already begging you to do. The key seam is that the trigger keys off "becomes tapped" rather than "attacks." That distinction is what turns a mediocre 2/2 into an engine piece: anything that taps it without sending it into combat refills your hand while keeping the body off the chopping block. A tap-to-activate cost, a controller's own tapper effect, crew, convoke, an untap-and-retap loop; each of those quiet taps becomes a cantrip without exposing it to blocks. The Merfolk Wizard typing matters because that tribe has long trafficked in tapping as a resource: lords that tap themselves to pump, islandwalkers that need to connect, the whole archipelago of tap-based aggression. Slot this into that shell and the moments you were already tapping this specific creature each pay a card on top. The restriction that keeps it fair is the body itself: a 2/2 dies to almost anything, and the engine only runs while it lives. Untap effects make it loop and accelerate the payoff; the smallest piece of removal makes it a four-mana speed bump that drew you nothing.