How do you get the mist form on castlevania nights symphony of the

You can find the power of Mist in the Colosseum. You mainly get to it as a prize after you defeat Richter's henchmen. When you have the Soul of Bat, head to the Castle Keep. If you keep going up just below the platform where you hit the switch, you can find the Form of Mist. This actually allows you to hold the power of Mist much longer than you originally could. It's pretty useful for those nasty sticky situations that you might run into.