Okay if I join with a 'void mage.' he would most likely be a c rank because of his lack of spells and training. 
He would have than ability to create rifts, which are a set of black rectangles with a line of light connecting them (if you go in one, you come out of the other one). He could eventual create pocket dimensions (witch are just empty space) and void blades/walls, which are a space of pure nothing.