Setessan Starbreaker

Green's tools against the enchantment problem have usually been spells you only want once there is something to break: hold them and they sit dead in hand until a target shows up. Stapling the effect to a creature reframes which problem it solves. A 2/1 for four mana is a tax no one pays for the body alone, but the body is not the product; the product is Aura destruction that can never be a blank draw. The trigger reads narrowly on purpose: it removes Auras, not enchantments at large, so it answers the menace green has the most cause to fear (a buffed attacker, a stolen creature, a Pacifism-style lock) without pretending to be broad noncreature removal. With no Aura on the table, you have still cast a creature that attacks, and the trigger simply finds nothing to do. The optional wording earns its place in the case people overlook: when the only Aura around is your own (a green pump aura on your attacker, say), "may" is what stops the enter trigger from forcing you to wreck your own permanent. That is the whole conversation here: a removal effect that also wants to be a creature, with a deliberately undersized frame absorbing the premium so the answer rides on a card worth drawing regardless. You give up the efficiency of a dedicated spell for the guarantee that the slot is never empty, and the small body is the receipt.