Banish from Edoras

Unconditional exile at five mana is a fair rate for white; unconditional exile at three mana is a bargain, and this card hands you that bargain any turn your opponent has committed a creature to the attack or spent it tapping for value. The whole design lives in the word "tapped." White's premium removal has always priced in the permanence of exile: no regrowth, no reanimation, no death trigger. What this adds is a tempo lever on top of the finality. It punishes the attack step specifically, since a creature that swings in is a creature you can answer cheaply on your own turn, and it quietly discourages tap-for-value abilities by turning every activation into a discount for you. The cost reduction is the entire tension: cast it proactively at full price against an untapped threat and you have overpaid, so the card wants you to hold it and let the opponent decide when it becomes efficient. That patience is the friction. You are trading the certainty of removing a blocker or an untapped bomb for the reward of removing an attacker or a tapped mana source at a discount, a wager on how the opponent will use their board rather than a clean point-and-shoot answer.