I'm confused, how dose the detriment rule apply to damage? It says it dose but doesn't explain how, at least from what I can tell.
Are you talking about negative damage, as in healing? If so is DM fiat the only thing keeping someone from making OP healing spells? I know this system isn't strict about balance, but still...
Or do you mean damage that hurts the caster and maybe even their allies? That makes more sense.