Serpent Skin

The flash clause is what turns this from a vanilla growth aura into something with a real combat function. Auras have always fought against the worst card disadvantage in the game: two-for-one yourself the moment the creature dies. Most green pump enchantments simply ate that risk and asked you to win fast enough to ignore it. Here the same instant-speed window that lets you ambush an attacker also dodges the blowout, since you can hold it back until a block resolves or a burn spell is already on the stack, then bank a regeneration shield on top of the stat bump. The regeneration is the part that pays for the aura's structural fragility: spend a single green and the enchanted creature survives the combat or the burn that the aura would otherwise have made worse. So the card collapses three jobs into one slot: a trick, a permanent buff, and recurring protection, all at a price you can hold open without telegraphing it. That it never saw the spotlight says more about how poorly auras compete with two-for-one-proof equipment than about the design itself, which is a tidy answer to the question every aura has to answer: what happens when they kill the thing you enchanted.