Against a prowess-based tempo deck, Consign to Memory's colorless-spell counter stops Mishra's Bauble and Cori-Steel Cutter triggers while replicate scales into a grindy race. Mystical Dispute is cheap and efficient against their blue spells. Ephemerate loses value since we need to be answering their threats rather than protecting our own in a race, and Thraben Charm's damage mode is inconsistent against a deck with many 1-toughness threats we'd rather handle with Solitude or Goblin Bombardment anyway.