Roy Mustang snaps his fingers accidentally (while wearing his gloves)
What people think will happen: fire, death, destruction
What will actually happen: a small spark
Why people are wrong: they think Roy’s Flame Alchemy actually creates flame, whereas what he’s alchemizing is the oxygen concentration of the air. Alchemy takes concentration and intelligence so he can’t accidentally move air particles around to make the air so oxygenated as to be flammable. The finger-snap just ignites the oxygen. If the air is normal, it’s not going to ignite.
Extra fun fact: you can probably tell if Roy Mustang is about to set you on fire. The air will feel intoxicatingly easy to breathe because it’s pure oxygen. During the war, Ishvalans probably learned to GTFO if they felt heady and energized.
Extra extra fun fact: Roy Mustang doesn’t need to set you on fire to kill you. He can probably just remove all the oxygen from the air around you, and you’ll suffocate.
The point of this post: flame alchemy is both really cool and really simple.
The kicker: to use flame alchemy effectively, you probably have to visualize the shape of the oxygen cloud that’s going to form. This probably requires a lot of focus.
I am: a nerd.