Dimir Terror leans on Tolarian Terror, cost-reduced by instants/sorceries in the graveyard, and Gurmag Angler's delve, so Crypt Incursion is valuable to exile their creature cards from the graveyard, denying delve fuel for Gurmag Angler. Breath Weapon sweeps their 1-toughness Sneaky Snacker and other small bodies for three mana. Hydroblast provides no value since they have no red spells, but Pyroblast can target their blue spells and Circle of Protection: Blue prevents damage from their blue sources. Keep Counterspell and Dispel active to fight over their own countermagic and protect your threats.