Mountain Goat

Landwalk is the oldest evasion mechanic in the game, the earliest answer to a question evasion would later solve a different way: how do you make a creature unblockable? The first solution made the answer depend on the opponent's deck rather than on the pilot's, and this 1/1 is that idea reduced to its barest form. Its entire pitch is conditional. Facing a deck without Mountains, it is a vanilla body with nothing to recommend it; facing one full of them, it becomes an unblockable trickle of damage. That binary defines the card. Mountainwalk hits hardest in a mono-red mirror, the one matchup where a tiny attacker is least likely to swing a game, and does nothing in the matchups where you would actually want a reliable way through. Later design quietly retired basic-land-walk as a maindeck consideration precisely because it punted the creature's value onto the metagame rather than onto anything the pilot controls. What remains is a clean historical artifact: proof that early design measured a creature's worth by the board it expected to face, before evasion became something you could rely on regardless of who sat across the table.