Mono-White Humans is a low-curve, go-wide aggro deck full of 1- and 2-toughness Humans (Dauntless Bodyguard, Kytheon, Hero of Akros, The Queen of Dale), so Withering Curse's -2/-2 sweeps much of their board at instant-sorcery speed for three mana, though note it won't kill Adeline, Resplendent Cathar or Arachne, Psionic Weaver which have higher toughness. Duress proactively strips key noncreature cards like Wedding Announcement from their sideboard plan or any removal before they commit creatures. Trim slower creatures to prioritize interaction and sweepers, since surviving their early pressure is the primary gameplan. Keep Fatal Push and Abrupt Decay in as cheap, efficient removal for their small Human threats.