This Colorless Prison/Ramp deck's entire game plan revolves around colorless spells like Kozilek's Command, The One Ring, and Karn, the Great Creator, all legal targets for Consign to Memory to strip away their card advantage engines. Erode provides hard removal for a resolved Ugin, Eye of the Storms or other big colorless threat that would otherwise run away with the game. Stifle can hit Karn's -2 ability but is often too narrow against their broader colorless-permanent-based plan, and Force of Negation competes awkwardly with our limited blue mana for their similarly-costed interaction, so we favor the more flexible removal and counter suite.