Quote Originally Posted by shinta|hikari View Post
But she wasn't training, at least not intentionally. She was just blowing shit up because she liked using explosion. That's what makes her funny!

And I think their world has game like levels and stats, which means that like Darkness's unreasonable toughness, they get it by leveling up (i.e. defeating monsters, finishing quests), not training normally. It's like how you won't level up in an RPG no matter how many times you swing your sword or cast Firaga if you don't kill anything.
There's no other way to train explosion magic than to make things explode. Who knows if she killed anything but critters and birds with the big explosion, but the castle surely suffered grand damage. Aside from some earth magic, explosion magic would be the only magic to damage structures so easily (relatively speaking). If causing major damage to a defensive structure gives you no experience, it's one shitty world. It's no use to compare this to an existing RPG since they all have static worlds. I mean, in a real scenario an explosion magician's very function could be to blow away the whole gate of an enemy castle to allow troops to get in.