Bubble Snare

The classic pacifism effect rebuilt around a subtler denial: rather than a "can't attack" clause, this locks the enchanted creature out of its untap step, which switches off both its offense and its defense while the body sits there untouched. What makes the lock work is the kicker, which functions as a dial rather than a switch. Unkicked at a single blue mana, it is a delayed answer that only earns its slot against a creature that is already tapped, since it freezes whatever the creature's current state happens to be. Enchant an untapped threat cheaply and you have not wasted the spell; you have simply granted it one last tap (an attack, an activation) before the lock takes hold. Pay the kicker and the same card taps the creature as the Aura enters, catching a fresh attacker or blocker outright without waiting on the opponent. That split gives the caster a real choice between thrift and reach on one card. What keeps it soft is everything an opponent can do to the enchanted permanent: sacrifice, blink, and bounce all shed the Aura and free the creature while trading down the caster's card, and any removal aimed at the body does the same. There is no combat-trick window here, since it resolves at sorcery speed; the entire flexibility lives in the kicker, letting one slot serve both a tight early curve and a late-game pin.