Llanowar Vanguard

A wall in dryad clothing, except it forgot to commit to being a wall. The defensive geometry is the tell: tapping for +0/+4 turns a fragile 1/1 into a 1/5, but only for the turn it spends its tap, which ties the survival window to the same resource the creature would otherwise use to attack. It can guard the ground or it can swing, never both in one turn. The ability carries no timing restriction, so the toughness is not locked to a main-phase declaration: you can declare the 1/1 as a blocker, then pump it after attackers have committed to the small body, letting them walk into a wall that was not there when they chose targets. Leaving the toughness contingent rather than printing it onto the stat line buys exactly that reactive window. Most early defensive bodies of this kind simply baked the toughness in and called themselves Walls; here the toughness is paid for with the activation and reverts the instant the turn ends, which keeps the option to attack as a 1/1 when nothing needs blocking. That dual posture, defender on demand and attacker the rest of the time, is most of what a fixed-toughness creature gives up, and most of why this one never aspired to be more than a green chump-blocker with an off-switch.