Ichthyomorphosis

The elegance here is that it answers a threat without killing it. Rather than exile, bounce, or destroy, this Aura reduces the target to a filing category: no abilities, no keywords, no relevant stats, just a blue Fish with a 0/1 body barely worth blocking with. That distinction matters against exactly the threats hard removal struggles with. A creature with indestructible loses that indestructibility along with everything else, so the enchantment itself never had to punch through it; a commander whose whole game plan triggers on dying never dies and never triggers; a graveyard-value engine sits inert on the battlefield instead of feeding a recursion loop. The Pacifism school of enchantment removal switches off attacking and blocking; this line goes further and erases the identity of the thing entirely, which is why it lands on text boxes that survive the more common answers. The cost is the familiar Aura tax: whatever value the creature banked on its way in is already spent and untouchable, the effect unwinds if the Aura is removed, and it commits a card to a target an opponent can reset by sacrificing or flickering. But as a piece of the ongoing project of turning threats into shrubbery rather than corpses, it sits alongside Kenrith's Transformation and Song of the Dryads: soft removal whose real job is deleting the abilities the format has learned to build around, and leaving the harmless husk on the table.