Here's a great way to collect a lot of orbs. After you finish the game's third mission, go back through and play it again. From the start, run past the statue into the first hall, where you can kill enemies to collect experience points and orbs. Then, seek out a hallway where a wooden wall stands. Break through the wall, where you can find a crystal. Break the crystal to collect an automatic 1,000 orbs. Then, exit the mission. This is a quick way you can repeat over and over again to collect as many orbs as you'd like (and some experience, too).