Colorless Prison/Ramp relies heavily on artifact mana acceleration (Grim Monolith) and artifact card-advantage engines like The One Ring, so Null Rod shuts off Grim Monolith's mana ability and The One Ring's tap-to-draw ability, slowing their whole gameplan. Force of Negation can be cast for free to counter Karn, the Great Creator, Ugin, Eye of the Storms, or Kozilek's Command on their turn, which is crucial since those threats are hard to interact with once resolved. Mockingbird loses value here since their best creatures are rare and expensive to copy meaningfully, and Wail of the Forgotten's modes are weak against a deck without much hand disruption or discard pressure needed. Keep Daze and Force of Will in as premium free countermagic against their big spells.