The casting process has several steps, the last of which is “pay costs in any order.” It’s only AFTER that final step is completed that the spell is actually considered “cast” for purposes of triggered abilities, and at that point, the Guttersnipe is already in the graveyard because you sacrificed it while paying the aforementioned costs. The trigger condition wasn’t met for its ability before it was sacrificed, so you won’t get that 2 free damage you may have been hoping for. Sorry!
Today’s Rules Tip written by Trevor Nuñez