Does a copy of a spell count as being cast for the purposes of storm?

Storm (CR 702.40) triggers when you cast a spell with storm, and it counts the number of spells cast before it this turn. A copy of a spell is never cast — it is placed directly onto the stack by a spell or ability (CR 706.10). Because copying is not casting, copies do not trigger storm and are not included in the storm count.

This means two things: (1) If you cast a storm spell and copies are created, those copies do not themselves trigger storm again. Storm triggers once from the original cast, and that single trigger produces all the copies. (2) The copies that appear on the stack from a previous storm spell do not increment the count for any later storm spell you might cast in the same turn.

The storm count is determined at the time the storm trigger resolves (CR 702.40a). It looks back at spells that were cast before the storm spell this turn — only genuine casts count, not copies already on the stack.

Example: You have cast two non-storm spells earlier in the turn, then you cast Grapeshot. Storm triggers and sees 2 previously cast spells, so it creates 2 copies of Grapeshot. Those copies deal their damage, but they were never cast — if you then cast a second Grapeshot somehow, its storm count is 3 (the two earlier spells plus the first Grapeshot cast), not 5.

Relevant rules: CR 702.40a (storm definition and count), CR 706.10 (copies are placed on the stack, not cast), and CR 601.2 (what it means to cast a spell).