In my opinion, flying is necessary in the game.

As part of a branch of telekinesis or wind. 

But without the ability to walk through walls

like some elementals and ghosts do.

It is necessary in order not to lose balance

and maintain a stable speed with complete

restraint (And in general it is cool and aesthetically pleasing). 

But instead, you can't use sprints,

use leg-activated magic,

some combat and assassin skills

, and it costs three skill points. 

In case of dazing and loss of consciousness 

it turns off automatically. 

The skill is switchable.

(P.S. It is good when multiclass students have skills that are well intertwined with each other, but it would be good to make skills that are not compatible with other classes for greater aesthetics and uniqueness. Flight is one such example.)

There are so much potential about air spell that weren't developed here. We can use air spells to knock enemies into wall or suck them together as vacuum force, dealing damage and stun them. We can use vacuum as insulated armor in order to reduce fire and ice damage. We can induce air into fire spell and amplify the damage. We can use "wind  cut" to assist melee. We can simply use air to blow away that annoying smoke created after using fire blast. I wish someone develop more about air spell man. They are so cool to be left inadequate like this