Fantastic Bounce

Blue has been throwing permanents back to their owner's hand since Boomerang, and at a flat four mana this reads like a slightly generous version of that: bounce a nonland permanent, refill your hand. What separates it is the discount clause, which turns the price into a reading of the board's posture. Target a tapped creature and the cost collapses to two mana, and the cards that end up tapped are the ones that have already committed: attackers you let through, mana dorks that spent themselves for the turn. The discount pays out exactly when an opponent has overextended, converting a middling rate into a real tempo swing that also cantrips. The sorcery-speed restriction is what keeps that cheap mode grounded. You cannot hold it up as a fake counterspell or a combat trick; you have to spend your own turn to unwind an attacker, refill, and reset the next combat math, so the tempo you buy is earned rather than a free blowout at instant speed. That conditional pricing is the more interesting layer, because it makes the spell wait for information before it commits: the battlefield tells you what it is doing, and the card charges you accordingly.