Living Armor

The scaling clause is the whole story, and it scales backward. Tying the counter count to the target's mana value means the creatures cheap enough to deploy on an early turn get almost nothing, while the only bodies that earn a real stack of +0/+1 counters are the expensive ones already least in need of help surviving. That inverts the usual logic of artifact protection, which exists to shield your fragile early plays; here the payoff demands a high-mana-value creature already in play and a reason to want it even harder to kill. And the deal carries no power at all, so it never converts a wall into a clock; it only buys toughness, and only by tapping and sacrificing the artifact for the privilege. The design reads as a stress test of what a one-shot tap-and-sacrifice artifact could safely do, with the answer landing on a purely defensive effect tethered to a cost structure you would rather not be paying. The cleanest line, a fat creature soaking even more counters, sits at a narrow intersection the rate does nothing to widen, which is what keeps this filed under curiosity rather than tool.