Grounded

Stripping flying off a creature is not removal: the body stays on the battlefield, keeps its power and toughness, keeps every other ability it had. What it loses is the option to leave the ground, which turns an unblockable evasive threat into a creature your ground forces can wall, race, or simply stand in front of. The design lineage runs through cards that punish one specific evasion stat. Green has plenty of ways to answer flyers from the sky down: reach blockers, the wave of "deals damage to each creature with flying" effects, the occasional fight spell that can connect with anything. What this offers instead is permanence at the individual level, neutralizing the single attacker that was getting through and keeping it grounded for the rest of the game rather than for one combat. That is the trade an aura like this makes against an instant: a spell that grants reach answers a flyer for a turn; this answers it forever, planted on the opponent's side of the table, freeing your blockers to do their job every turn after. The catch is the narrowness any pure flying-hate aura carries: against a creature already walking the ground it is dead, and against a board with no flyers it never gets cast. That conditionality is the price of the permanence, and it is why an effect this cheap stays honest.