Rustvine Cultivator

The trick here is that the ramp is stored, not immediate. A conventional mana dork earns its keep the moment summoning sickness wears off: tap it, get a color, cast something. This one asks you to bank turns first, spending an activation to load an oil counter before it can spend one to untap a land. It is ramp on a delay, and that delay pays for the payoff: a fresh copy does nothing but sit and charge, and each land untap costs a counter you had to invest an earlier tap to build. Because the untap frees a full land's worth of mana rather than a single dork's color, the value climbs with the cost of the land it unlocks, but the tempo cost of charging keeps that from becoming a turn-two explosion. This is a two-turn setup at minimum before any acceleration arrives. The 1/2 body matters more than a mana creature's usually does: it survives the incidental pings that would kill a 1/1, which is the difference between an engine that keeps charging through a cluttered board and one swept off it before the reservoir fills. Note that the counters are welded to the creature itself; there is no shared currency here, no spending the charge elsewhere. It is a self-contained battery whose only outlet is the land untap, built for grindy green decks that can afford to wait on their mana rather than sprint on it.