Cat Collector

The clever part is the self-priming. Most lifegain payoffs sit in a deck as dead weight until you assemble the other half; this one arrives already holding it. The Food token it makes on entry is a lifegain trigger you can crack whenever you like, so the second ability, the once-per-turn Cat that comes when you first gain life during your own turn, starts firing off the card's own body without any other pieces committed. It builds its engine and its fuel into a single three-drop. What keeps it from snowballing too hard is the turn-bound clause: the reward only cares about the first life you gain on your turns, so lifegain on an opponent's turn (cracking the Food at instant speed on their end step, or a drain spell resolving during their combat) does nothing to make Cats. Every gain after the first each of your turns is dead too. The payoff rewards steady incidental life across many of your turns rather than a single burst. The Food itself is slow (a sacrifice for three life, at a mana cost), which is the point: it is a guaranteed but unhurried trigger, not a combo enabler. This is the shape white lifegain tokens have been drifting toward for a while, where the reward is small, repeatable, and tied to a cadence rather than a total, and it packages that idea at a rate a creature can carry on its own.