Let’s say your opponent resolves a ‘Goyf on turn 2, with nothing in the graveyard (yes, please suspend your disbelief for a moment). You’re holding a Tarfire, and you have the untapped Mountain to use it. Don’t.
While Tarfire will deal “lethal” damage to the Tarmogoyf, state-based-actions aren’t checked until the spell has fully resolved (this is why, for example, a Psychosis Crawler doesn’t die when you cast Wheel of Fortune and your hand is empty for a short time). By the time SBAs come around, Tarfire has fully resolved and is in the graveyard, meaning there’s a Tribal card type and an Instant card type in your graveyard, so you have fed your opponent’s ‘Goyf a free +2/+2, and it is now a 2/3 with 2 damage marked on it, and lives. So, bad time.
Well boys and girls, that wraps up today’s Rules Tips. Once again, I wish you good luck, good topdecks, and Safe Passage to all of you headed for Denver this weekend. And remember: When in doubt, call a Judge!
Today’s Rules Tip written by Trevor Nuñez