Esper Ephemerate leans on artifact value creatures like Baleful Strix, Refurbished Familiar, and various artifact lands/bridges, so Annul can proactively counter these or their Giant's Boulder before they generate value. Steel Sabotage provides flexible disruption, either countering an artifact spell or bouncing a problematic permanent like Refurbished Familiar to reset their board. Deep Analysis and Sleep of the Dead are too slow against a grindy value deck that will out-card-advantage us if we're not proactive with our counterspells. Keep the full Counterspell and Dispel suite since stopping Ephemerate loops on Baleful Strix or Mulldrifter is essential to winning the long game.