Cryoshatter

Removal that fires on a delay is the tradeoff here: for a single blue mana, this Aura doesn't kill the creature outright but arms it, converting the two most routine things a threat does into a death trigger. Attacking taps the creature and detonates it; taking any damage, whether from combat or a burn spell, detonates it too. The -5/-0 is the bridge that closes the gap while you wait, gutting the creature's offense so hard that even a sizeable body stops threatening a race, and often the enchanted creature just sits there defanged, because any use gets it killed. That's the wrinkle blue rarely gets to exploit: this is a color that traditionally answers creatures by bouncing or countering them, not by leaving them on the battlefield in a lethal holding pattern. Because the destroy clause keys off tapping and damage rather than a stat comparison, toughness has no bearing on the out; the only genuine escape is something that keeps the creature from dying to destruction at all, like indestructibility, or a way to move it out from under the Aura. The aggressor still has to spend that answer or accept that their creature is now a liability. The pressure it creates is psychological as much as mechanical: the opponent knows exactly how the creature dies and has to route their whole game plan around never letting it happen.