Flatman

A 1/10 body is a joke that only pays off with the activated ability, and the whole design is a single lever pulled twice: pay to become a 10/1, then pull it back. What that swing actually buys is a firewall that can turn into a haymaker at instant speed. Left alone, this blocks nearly anything and dies to nearly nothing; on your terms, it flips into a beater that hits for ten and shrinks back out of burn range on your opponent's turn. Green is comfortable stacking toughness this lopsided, but the color rarely hands out a way to convert a wall into a clock, and here the switch is the entire conversion mechanism, which is what sets the card apart from a big dumb defender. The repeatable, cost-attached flip is what keeps the trick from running away: at a pop it is not free, and a stalled board with green mana open asks the opponent to guess which stat is live before committing to combat math. It is a defensive shell carrying its own offense in reserve, sized so the same creature reads as unkillable blocker or glass-cannon threat depending entirely on whose turn it is and how much mana you have available. Everything worth thinking about lives in that one toggle and the timing around it.