Downpour

Tapping is the gentlest thing a defensive trick can do, and that gentleness is exactly the point: rather than killing an attacker or fogging the whole turn, this answer reaches in before combat and quietly removes up to three creatures from the math. The window is what gives it teeth. Cast it during your opponent's beginning of combat, before attackers are declared, and the tapped creatures simply cannot attack that turn, blanking a third of an aggressive board's offense; cast it on their end step and you strip blockers for your own swing the following turn. It is a Falter effect run in reverse, tapping their team down instead of pushing yours through, and the "up to three" flexibility means a fixed two-mana price buys anything from a single point tap to a board-wide commitment without the spell ever rotting in hand. The catch is that nothing dies. Everything it taps untaps next turn, so this buys a turn rather than solving a problem, which is the trade cheap tempo interaction has always made: a delay sized to swing a single combat, not to win a game. That ceiling is also its honesty. It asks the pilot to know which turn matters, and to fire the spell in the right step of it, since a creature tapped after attackers are declared still gets to swing.