Counter target spell with converted mana cost X. (For example, if that spell's mana cost is, X is 5.)
7/1/2013 Alternative costs, additional costs, cost increases, and cost reductions don’t affect a spell’s converted mana cost.
7/1/2013 If the target spell has in its mana cost, include the value chosen for that X when determining the value of the in Spell Blast’s mana cost. For example, if you wish to counter Volcanic Geyser (a spell with mana cost ) whose X is 7, you’ll need to choose 9 for Spell Blast’s X and pay .