Hua Tuo, Honored Physician

The constraint is the whole game with this one: regrowth that returns nothing to your hand, only to the top of your library, and only during your own turn before combat. Green has always paid for recursion with friction, but most of its graveyard-to-hand effects (Regrowth, Eternal Witness) hand you the card outright. Hua Tuo trades immediacy for repeatability: an untapping engine that buys back a creature every turn, at the cost of a draw step and a strict window. That window is doing real work. Restricting the activation to your own turn before attackers are declared means you cannot rebuy a blocker on your opponent's turn or hold up the ability as a combat trick, so the body stays a defensive 1/2 while the engine churns on a slow clock. It also means that unless you activate it in upkeep before drawing, the card you top-deck arrives on next turn's draw, not this one, which turns the ability into a deliberate setup rather than a panic button. The historical texture is its origin in the Romance of the Three Kingdoms cycle, a horizontal block where legendary names were attached to grindy, tap-to-activate utility designs rather than bombs. Hua Tuo is the physician archetype rendered literally: a healer who keeps your fallen creatures cycling back to the front, never hurried, never wasted, asking only that you have the patience to wait a turn for the return.