Once you have your Magic stat to 20, you will unlock the Training Mission in the Dojo - complete this to unlock the Msytic Arts in the Skill Tree.
Each Mystic Art costs 5 points.
The Dojo Mission is 3 waves of enemies, using skills/talismans you cannot change.
You fight against 2 x Sentries, then an Onryudo, lastly a Nue.