Shrine of Boundless Growth

This belongs to a cycle of five mana-storing shrines, each charging off a color and a passive upkeep tick, and the green one is the patient one of the set. Every green spell you cast adds a counter, and so does the start of each of your turns, so the artifact does the thing green has always done best: it grows quietly while the table watches the more threatening permanents. The payoff is a single burst of colorless mana equal to the counter total, released only by sacrificing it, which makes the card a deliberate slow burn rather than a recurring ramp engine. That sacrifice clause is the cost that pays for the open-ended ceiling: there is no upper bound on how large the payout gets, but you get exactly one detonation, and you have to choose the turn to spend it. The colorless output is the honest part of the design. It will not fix your green into double-pip costs, but it floods a single turn with enough generic mana to power an oversized X spell, an expensive activated ability, or a colorless bomb that a normal curve could never reach. It rewards a deck that wants to build toward one explosive turn and is willing to wait several turns of slow accrual to get there, which is a narrower ask than most ramp pieces make, and a more dramatic one when it lands.