Frilled Sandwalla

The oracle answer to the perennial problem of the turn-one creature that goes dead by turn four: a 1/1 that carries a mana sink inside its own body, so the single green you spent on turn one keeps buying two more power and two more toughness whenever you have the spare mana. The "once each turn" clause is the restriction doing the load-bearing work. Without it, the same activation would still cost mana every time, but you could stack pumps across a single combat step and dump a whole turn's worth of open mana into one unblocked attacker for a surprise kill. Capping activation to one pump per turn turns that burst potential into a slow, repeatable threat: it pressures the board across multiple turns instead of demanding all your mana at once, and it keeps trading well against decks trying to grind you out. This is the pump-on-demand lineage in its plainest form, a firebreathing-style outlet grafted onto a cheap green body that has existed since the earliest sets: cheap to deploy, never a dead draw, and a place to spend mana the moment a game stalls. The lizard wants nothing from your other cards and rewards nothing in particular. It simply refuses to become irrelevant, which for a one-drop is the entire job.