Imperiosaur

The trade here is deliberate and unusual: a 5/5 for four mana, a body that runs ahead of green's normal curve, in exchange for a casting restriction that punishes the very mana technology green is best at. The spell only accepts mana from basic lands, which means every nonbasic that defines a polished green manabase (the dual lands, the fetch targets, the man-lands, the value lands that ramp and fix) is dead toward casting it. It is a design that inverts the usual cost structure. Most undercosted creatures pay with a downside on the battlefield: a drawback ability, a tempo loss, a body that betrays you. This one is clean once it resolves; the entire bill comes due in deckbuilding, where you must forgo the manabase sophistication that would otherwise be free. The result is a card that rewards a stripped-down, basics-heavy mono-green shell and actively resists the splashes and fixing that modern decks treat as default. It is gated not by what it does but by what mana you are allowed to feed it, a restriction that reads as a footnote and functions as the whole balancing act. The flavor of a primal lizard that refuses anything but raw, unprocessed land is doing real work here: it will not eat from your refined manabase.