Agoraphobia

The pseudo-removal that pretends an attacker out of relevance instead of killing it. Dropping a creature's power by five does not change the board the way destruction does: the creature stays, keeps its toughness, keeps any combat or activated abilities that do not scale off power, and the moment the Aura leaves, the body is whole again. What that buys is a defensive tempo swap, neutralizing the biggest attacker on the other side while the -5/-0 holds continuously, no upkeep tax required. The self-return clause is the real design hinge. Most Auras commit you permanently and evaporate to a two-for-one when the creature dies or eats enchantment removal; paying to pick this one back up turns a single card into a redirectable soft-lock, moving from an old threat to whatever new one lands and dodging the classic card-disadvantage risk by walking off the board on your terms. The cost of all that flexibility is that it never actually solves the problem. Once the Aura is gone (bounced, destroyed, or moved), the creature snaps back to full power, so this is a holding action and a clock-buyer rather than a closer. It is blue's characteristic refusal to remove a thing in favor of rendering it temporarily harmless: the answer stays in your hand as leverage rather than in the graveyard as a resolved question.