Easy to get. Don't kill all the monsters in the early level's but carry on with the story. Once you get to Populi, a city populated by trading mice, you should have leveled up Aurora enough to have the Starlight Attack All skill. Go back to the early levels (I did it on Monastery) and find a creature. Make sure you are fighting 3 foes and then use Defend until you have enough time to use Starlight all, as it takes a long time to cast. With mist creatures it should kill them all three first time round. If not you will have weakened them enough to take them out with another attack.