Halo-Charged Skaab
Mill two, then rebuy: the enters trigger takes something spent from your own bin and threads it back onto the top of your library, ready to draw next turn. That symmetric self-mill is the price of the retrieval, and it does real work in both directions. The mill hits both players, which can feed an opponent's graveyard as readily as your own, but the payoff clause only rebuys an instant, sorcery, or battle card for you: it is a spell-recursion body, not a creature engine, and the graveyard it wants to fill is the one full of the burn, counterspell, or removal you already cast. The battle-card clause is the tell for when this was made; battles are a young card type, and stapling their recursion to a common-shaped 4/4 was a way to make sure the mechanic had a home. Everything hinges on the "may": you choose whether to top-deck the retrieved card, so a whiffed mill costs you nothing but a couple of cards off both libraries. The body backs it up honestly, a 4/4 for five that blocks and attacks while the recursion sits in reserve, so the card does not fold into pure value the way a smaller do-nothing enabler would. It is a modest, well-behaved take on graveyard-to-hand-adjacent recursion, wearing enough stats to matter on the board.
