Spider Climb

The conditional flash clause is the whole point, an early experiment in pricing the timing window rather than the effect. Most flash spells charge mana for the privilege of casting at instant speed; this one charges the durability of the enchantment. The body it grants is purely defensive: more toughness and reach, the classic answer to fliers and the alpha strike. Cast at sorcery speed, it behaves like any other Aura and stays attached permanently. Cast in response, ambushing an attacker the way a true instant would, and the Aura sacrifices itself once the dust settles: the creature keeps the toughness and reach through that combat, then loses the enchantment when the turn ends. The card hands you instant-speed access at the cost of permanence, a trade an ordinary Aura's sorcery-speed restriction would never permit. The self-sacrifice does the balancing work a higher mana cost or smaller stat boost would do elsewhere, and it does it without touching the rate printed on the front of the card. The strategic question is not "can I afford this" but "do I need this blocker to stick around, or just to survive this attack?" Use it as a permanent buff at sorcery speed, or spend it as a one-shot ambush at instant speed, and let the timing decide which.