Skeletal Vampire

What you are buying is a self-sustaining token engine that refuses to die, with the 3/3 flying frame functioning mostly as the housing for it. The enters trigger drops two Bats immediately, but the machine is the pair of sacrifice abilities pulling against each other: spend Bats to make more Bats, or spend Bats to regenerate, and you pick which the board needs most each turn. That loop turns a flier into a resilient swarm-maker, grinding out the flying chaff a token-payoff deck wants in bulk. Regeneration is what keeps the engine durable: hold a single Bat and the creature shrugs off destruction-based removal and damage-based sweepers, asking an opponent to commit two answers where they planned for one. The same recursion is the constraint, since every regeneration shrinks your swarm and every fresh batch costs real mana, so the engine is only as strong as the time you can afford to feed it. It sits in the long line of black creatures that pay for value by spending bodies, the aristocrats lineage where each token is both blocker and ammunition, and it remains one of the cleaner cases of a creature that is its own sacrifice fodder, its own removal insurance, and its own win condition without a second card to close the loop.