“Dimir Control is a blue-black control deck: Counterspell, Spellstutter Sprite and Dispel for permission, Snuff Out, Cast Down and Agony Warp for removal, Lorien Revealed, Brainstorm and Ninja of the Deep Hours for card flow, and Thorn of the Black Rose (the monarch) plus Baleful Strix to grind out long games. Its maindeck has no red cards, so anti-red cards (Hydroblast, Blue Elemental Blast) have no targets. Pyroblast and Red Elemental Blast are the opposite: they hit BLUE spells and permanents, so they are live against Counterspell, Dispel, Brainstorm, Lorien Revealed, Spellstutter Sprite, Faerie Seer, Ninja of the Deep Hours and Baleful Strix; the deck having no red cards does not make them dead. Its only artifacts are the artifact creatures Baleful Strix and Mukotai Ambusher, which are legal targets for "destroy target artifact" effects, so artifact hate such as Steel Sabotage is narrow but not blank.”
Missing sideboard cards? The full 15-card sideboard runs about $44.89.
Buy sideboard on ManapoolMono Red Madness is almost entirely red, so Blue Elemental Blast and Hydroblast come in as premium counters/removal against Lightning Bolt, Fiery Temper, Guttersnipe, Kessig Flamebreather and Voldaren Epicure. Dispel is too narrow here since it only stops instants, missing Faithless Looting, Fiery Temper's madness trigger timing, and Kessig Flamebreather's damage trigger. Plunder the Trollshaws and Augur of Bolas are too slow against a deck trying to race with damage triggers. Keep Snuff Out, Cast Down and Agony Warp in to answer their small creatures and race their burn with life-neutral removal.
This is the mirror, so Annul comes in to counter their Baleful Strix and Mukotai Ambusher, the only artifact spells either deck plays. Plunder the Trollshaws is replaceable since card flow is less urgent against a deck with identical removal and counters. Cutting one Mukotai Ambusher and one Thorn of the Black Rose trims redundant late-game bodies since both players grind similarly and the monarch is easily taken back by their own Thorn of the Black Rose. Keep Counterspell, Snuff Out and Dispel at full count since counter and removal wars decide this matchup.
Spy Combo wants to assemble a critical mass of mana dorks and engines (Overgrown Battlement for mana, Winding Way and Lead the Stampede for card selection) before going over the top with Troll of Khazad-dum and Lotleth Giant. A second Arms of Hadar helps against their small dorks, since it kills Elves of Deep Shadow, Quirion Ranger and Gatecreeper Vine, though it will not kill the bigger walls like Wall of Roots, Overgrown Battlement or Saruli Caretaker. Okiba-Gang Shinobi punishes their grindy draws by making them discard two cards when it connects, which is relevant since they have few ways to interact with an unblocked ninja. Agony Warp and Extract a Confession are the weakest removal here: -3/-0 or -0/-3 does not kill Troll of Khazad-dum or Generous Ent, and Extract a Confession lets the opponent choose which creature to sacrifice, so they will simply give up a mana dork or wall. Keep Counterspell in to stop their top-end threats before they resolve. Keep Snuff Out in as well, but remember it cannot target black creatures such as Troll of Khazad-dum or Lotleth Giant, so it is best aimed at green creatures like Generous Ent.