Necromancer's Familiar

Hellbent asks you to run yourself out of cards, and this design leans into that demand from both directions at once. The lifelink half is passive: keep an empty hand and the flying body starts clawing life back, exactly the payoff a discard-heavy deck wants once it has emptied its resources. The activated half is where the card gets pointed, because it invites you to pitch cards deliberately to make the creature indestructible for a turn, and each activation taps it, so the protection is bought against tempo rather than mana alone. That tension is the whole engine: you are converting cards you no longer want into an unkillable attacker, and the same discards that shrink your hand toward hellbent are the fuel for the ability. The Bird Spirit slots naturally into black shells that empty the hand for profit: madness enablers, delirium counters, anything that treats a discarded card as a resource instead of a cost. The indestructible grant has clean limits, though: it does nothing against removal that bounces, exiles, or forces a sacrifice, and the tap clause means you cannot both protect the attacker and hold it back on defense. It is a reward card wearing an evasive body, made for the plan where losing your hand was always the point.