Mono-white Aggro goes wide quickly with cheap creatures like Thraben Inspector, Novice Inspector, and token generators like Battle Screech, so Loyal Sentry trades with and destroys any attacker it blocks, giving you a reliable way to remove their best threat in combat. Ethereal Haze prevents all creature combat damage for a turn, which can blank a wide alpha strike after Ramosian Rally or Guardians' Pledge pumps their team. Dispel is weak since their deck has very few relevant instants to counter, and Fanged Flames is replaceable by the more proactive blocker. Keep Skred and Counterspell as your main removal and disruption, since Skred scales well against their smaller creatures as the game progresses.