Colorless Prison/Ramp wants to lock you out with Trinisphere while using Urza's Saga, Ancient Tomb, and Grim Monolith to power out The One Ring, Karn, the Great Creator, and Ugin, Eye of the Storms, so disrupting their mana and answering their engines is critical. Hurkyl's Recall is a huge tempo swing, bouncing their entire artifact mana base (Grim Monolith, Mox, Urza's Saga tokens) back to hand and setting them back several turns. Engineered Explosives can answer a Trinisphere or an early artifact mana rock, and the extra Force of Negation helps stop The One Ring or Ugin before they take over the game since this deck has almost no way to interact with your counterspells otherwise. Daze and Boomerang Basics are cut since they're too low-impact against a deck that isn't racing you on the battlefield with creatures.