Dimir Terror is another all-blue-leaning deck (Tolarian Terror, Counterspell, Brainstorm), so Red Elemental Blast is well positioned to counter their Counterspell or destroy an early Sneaky Snacker/Tolarian Terror before it grows out of hand. Dispel adds another way to protect your Seething Song or Glimpse the Impossible from their permission suite. Note Tolarian Terror has Ward {2}, so use Red Elemental Blast on it proactively as a counter to the spell rather than trying to destroy it once it resolves, since the ward tax will eat your mana. Trim First Day of Class and a Seize the Storm copy to make room for the extra interaction against their counterspells.