Solid Footing

The interesting clause here is the conditional that only fires when the enchanted creature already has vigilance: turn on that keyword and the creature stops assigning damage equal to power and starts assigning damage equal to toughness. That flips the entire cost-benefit of building a defensive body. Big-toughness, small-power creatures (walls and the fat blockers that normally sit back doing nothing offensively) suddenly hit for their bulk, and the +1/+1 nudges both numbers in the same helpful direction. The design rewards a very specific board state: you need vigilance from somewhere else, whether printed on the creature or granted by another effect, before the toughness-as-power line means anything. Without it you have paid one mana for a modest stat bump. The flash is what keeps this from being a pure build-around; it lets the aura come down as a combat trick during a block, converting a chump-blocker into a lethal one after attackers are declared, or ambushing an attacker with a defender that suddenly punches back. It is a piece that asks you to think about which of a creature's two combat numbers you actually want to be the relevant one, and it only pays off for players who have arranged for vigilance and lopsided toughness to coexist on the same body.