Dimir Control has no red cards, so Hydroblast has no targets and stays in the sideboard. Pyroblast is live, though: Counterspell, Spellstutter Sprite, Faerie Seer, Brainstorm, Baleful Strix and most of their other key cards are blue, so it can counter their permission or destroy their flyers. Graveyard hate like Nihil Spellbomb has little to do here beyond Plunder the Trollshaws' flashback, so we trim it. Extract a Confession makes them sacrifice a creature of their choice, or the creature with the greatest power if we collect evidence. It is a cheap way to thin their small creature base while we push for lethal, and evidence mode becomes more available as the game goes long. Toxin Analysis and a Thoughtcast are the slowest pieces against their grindy removal-and-counter plan, so they make room. We want to keep maximum pressure and card velocity, so the core engine stays untouched. This is mostly a tempo matchup where we out-race their permission before Counterspell and Snuff Out can keep up.