Elves goes wide extremely fast with mana dinks like Llanowar Elves and Fyndhorn Elves before closing with Craterhoof Behemoth or Natural Order, so discard spells that take one card rarely keep pace. Collective Brutality's -2/-2 mode can cheaply kill a single mana Elf like Llanowar Elves or Fyndhorn Elves, and Bitter Triumph answers their bigger threats like Eladamri, Korvecdal or an Atraxa put onto the battlefield with Natural Order. We cut two Unmask and two Cabal Therapy since by the time we'd cast them, Elves has often already deployed its full hand via Gaea's Cradle mana.