Walker of the Wastes

The whole gambit is the in the cost and the basic land that feeds it. That colorless requirement demands a source of true colorless mana, which the tribal payoff resolves with the same card type it scales off: the more Wastes you run to pay for the body, the bigger the body gets. It is a closed loop, a creature whose deckbuilding tax is also its reward, asking you to flood your manabase with a single named basic and then cashing those lands out as combat stats. The catch is that the clause only counts lands named Wastes, not any colorless source, so the payoff lives or dies by how many of one specific land you can justify. A 4/4 trampler is the flat floor; the ceiling is a function of how committed you are to the gimmick. As a piece of mechanical writing it is unusually literal about the colorless-matters theme: rather than rewarding generic devotion to the colorless mana type, it rewards a roll call of identically named lands, turning a deckbuilding constraint into a scaling clock. Trample is the closer that keeps the upside from being chump-blocked into irrelevance, which matters precisely because the whole reason to build around it is to land a body large enough that a single creature cannot stop it.