Dimir Terror is a tempo-control deck that wins by countering your key combo pieces and deploying large delve threats like Tolarian Terror and Gurmag Angler ahead of curve. Red Elemental Blast is the key sideboard addition — it answers their Counterspells, Brainstorm, and Tolarian Terror, letting you push Inside Out through their disruption or neutralize their biggest threats cheaply. Additional copies of Prismatic Strands come in as a fog to survive their creature clock and buy a critical turn to assemble the Tireless Tribe plus Inside Out combo. Lightning Bolt is largely ineffective here since their threats are too large to kill efficiently, and Abandon Attachments and Sandstorm Eidolon contribute little against a deck with almost no relevant auras and creatures that survive one damage. Post-board, expect four Hydroblast from them, so prioritize protecting your combo window by holding up Red Elemental Blast mana to fight through their permission and keep Loran's Escape available to shield Tireless Tribe from Snuff Out or Cast Down.