"Barrel Dragon" + "Blowback Dragon"
Once per turn: You can toss a coin 3 times and destroy as many monsters on the field as possible, but not more than the number of heads.
Rulings
Individual Card FAQs
You must destroy as many monsters as possible based on the number of Heads you flip. If you flip 2 Heads, and the only monsters on the field are 1 of your opponent's monsters and your “Gatling Dragon”, you must destroy both monsters. If there are only 2 monsters on the field and you flip 3 Heads, destroy both monsters.
You cannot activate “My Body as a Shield” as a chain to “Gatling Dragon” because it has not yet been decided if any monster(s) will be destroyed or not.