Dragon's Fire
Instant
As an additional cost to cast this spell, you may reveal a Dragon card from your hand or choose a Dragon you control.
Dragon's Fire deals 3 damage to target creature or planeswalker. If you revealed a Dragon card or chose a Dragon as you cast this spell, Dragon's Fire deals damage equal to the power of that card or creature instead.
Campbell White
Rulings
A Dragon card is a card with the creature type Dragon in its type line. Similarly, a creature on the battlefield is a Dragon if it has the Dragon creature type. A card that has "Dragon" in the name (such as Dragon's Fire) isn't a Dragon card unless it also has the Dragon creature type.
(wotc • 2021-07-23)
If you chose a Dragon you control, use that Dragon's power as Dragon's Fire resolves to determine how much damage is dealt. If the Dragon you chose is no longer on the battlefield as Dragon's Fire resolves, Dragon's Fire will deal damage equal to the power it had the last time it was on the battlefield.
(wotc • 2021-07-23)
Rulings
A Dragon card is a card with the creature type Dragon in its type line. Similarly, a creature on the battlefield is a Dragon if it has the Dragon creature type. A card that has "Dragon" in the name (such as Dragon's Fire) isn't a Dragon card unless it also has the Dragon creature type.
(wotc • 2021-07-23)
If you chose a Dragon you control, use that Dragon's power as Dragon's Fire resolves to determine how much damage is dealt. If the Dragon you chose is no longer on the battlefield as Dragon's Fire resolves, Dragon's Fire will deal damage equal to the power it had the last time it was on the battlefield.
(wotc • 2021-07-23)