Dimir Excruciator wants to Duress/discard our hand and wipe the board with Deadly Cover-Up, so protecting our threats on the stack matters more than cheap removal. Impractical Joke is weak here: its 3 damage only kills Seasoned Cryomancer (2/2) or hits The Theorist, Jace Beleren, while Superior Spider-Man (4/4), Deceit (5/5) and Uldaros Theorix (5/5) all survive it. Spell Snare only counters a spell with mana value 2, so it catches Bitter Triumph, Theorix Charm and Strategic Betrayal, but not Duress or Requiting Hex (both mana value 1). That is narrow, so we cut one copy and keep the other. Spell Pierce is more flexible: it taxes Duress, Requiting Hex, Bitter Triumph, Theorix Charm and Deadly Cover-Up, which helps protect our Eddymurk Crab and Hearth Elemental from removal. Disdainful Stroke answers their expensive plays (mana value 4 or greater), such as Deadly Cover-Up, Uldaros Theorix, Deceit, Superior Spider-Man and The Theorist, Jace Beleren. It can't hit their cheap removal. Flashfreeze only counters red or green spells and they are blue-black, so it has no targets and stays in the sideboard.