Cryptolith Rite

Earthcraft turned creatures into mana but kept the basic-land clause that made it a combo piece, and tapped only for one color. Strip that clause, widen the output to any color, and you have an engine that converts a board into a treasury rather than a loop: every creature you control becomes a fixed-up mana source. The catch lives in summoning sickness. A fresh token is a body now and a mana source next turn, so the payoff lags a beat behind the board's growth. That delay is what keeps this from being a degenerate ramp spell and steers it toward decks already committed to a wide, persistent battlefield, where the question is less about acceleration and more about what a swarm of small creatures should become: a five-color top-end, fuel for a sacrifice sink, a way to pour an entire turn's worth of bodies into one payoff. It does nothing on an empty board, which is the honest cost of an enchantment that asks the rest of the deck to supply the creatures. In the right green go-wide shell it functions as a second mana base layered over the battlefield, folding color-fixing and acceleration into one permanent that scales precisely with how invested you already are in going wide.