Skyshroud Archer

Activate it during the opponent's combat and a flier loses a point of power and toughness until end of turn, enough to drop most early evasive creatures into the graveyard outright. Because it can fire at instant speed on any turn and resets every time the body untaps, it taxes any plan that leans on a single small flier to apply pressure: the archer keeps loosing arrows at the part of the battlefield green otherwise cannot touch, and it can ambush an attacker mid-combat rather than waiting for sorcery timing. This belongs to the era when green's anti-air had to arrive stapled to a creature rather than printed as a spell, and the targeting clause is exactly what balances the rate. It only touches creatures with flying, so it sits dead against any ground deck and turns useless the moment a flier grows large enough to shrug off the shrink. That narrowness is the whole point: green pays for reaching into the sky with conditions, and the verb here matters far more than the 1/1 body carrying it. The design quietly hands green a recurring removal effect, the thing the color is famously short on, without demanding a sacrifice or a death trigger. All it asks is that the opponent commit to the air.