Locked in the Cemetery

Pacifism keeps a creature from attacking or blocking; this Aura takes the harder line, keeping the creature from untapping during its controller's untap step. The interesting wrinkle is the conditional tap on entry: land it when your graveyard is stocked and the creature locks down tapped, out of every combat and every tap-based ability window unless another effect untaps it. Miss the graveyard count and you catch the creature in place but not necessarily disabled, so the enchantment rewards the slower, self-milling blue decks that fill their yard early rather than the aggressive ones that want an answer on turn two. That threshold is what balances an otherwise permanent hard-lock: the full effect is gated behind a deck built to reach five cards below, and the payoff is a removal-adjacent Aura that never actually removes anything. The creature stays on the battlefield, still countable for its controller, still a legal target, but functionally inert for as long as the enchantment sticks. It answers the threats that punish exile-based removal and the recursion decks that want their creature to die, since a creature that never untaps is neither dead nor doing anything.