Yeah, I learned that pretty early game. Fire Rune can be really solid for an opener. Though even I'd prefer to send off some thundery magic.

I seem to have all the stars now (At least that are collectable for now), so I've just been hitting hidden chests (I know I can get a thunder off Siren, I just stopped paying attention during the boss fight and got myself killed, didn't save the THunder. ) at the start of chapter 5, leveling so me of the weaker dudes in case of Large scale battle.