Narcolepsy

Soft removal that never removes anything: the creature stays on the battlefield, keeps its triggered and activated abilities, and simply spends every turn it would matter lying on its side. The lock is recursive: on each upkeep, any creature that slipped free during the untap step is re-tapped. That "if untapped" clause is the entire design. Pacifism shuts a creature off by forbidding combat; this works instead by exhausting the resource combat needs. The critical detail is where the check sits in the turn order: untap, then upkeep, then combat. The trigger resolves during upkeep, before the combat phase ever begins, so even a creature with vigilance gets tapped before it can be declared as an attacker; vigilance only matters once a creature is already swinging. The same timing is why this is no kinder to a defensive wall than to an attacker: the trigger resolves on the enchanted creature's controller's upkeep, leaving it tapped through their following turn, and a tapped creature cannot be declared as a blocker. The single genuine escape is an untap effect the controller can fire at instant speed after the trigger resolves, and even that fails next turn unless repeated. A flash-in or end-step trick buys nothing either: anything that arrives untapped is simply tapped on the next upkeep before it can act. Against any creature whose job requires it to be untapped for combat (attacker or blocker), this is a clean two-mana answer that holds it functionally dead while the aura sticks; a tap-ability engine, however, can respond to the upkeep trigger and still fire once each turn cycle.