Dimir Excruciator's plan revolves around discard (Duress), removal (Requiting Hex, Bitter Triumph), and a grindy Doomsday Excruciator/Day of Black Sun late game, so keeping your threats alive with Secret Identity and Shore Up is key to closing the game before they stabilize. Spell Pierce punishes their cheap disruption spells when they're tapped out on turns 2-3. We trim slower pump effects that don't help you race their removal-heavy plan.