[Champion Concept] Channel Mage (Please Read)

This is just a rough draft and I would appreciate feedback both positive and negative.

The Idea for this champion came from wanting to create a champion who is highly rewarded for having good positioning. I was thinking like a shadow mage who has to channel his energy before he can cast his spells. I created a sample kit and some scenarios to kind of showcase what a champion like this could offer. (please note the numbers you see are only placeholder numbers)

passive - when unseen by enemy champions, the next offensive spell or basic attack deals 10% bonus damage.

Q - after channeling for 1.5 seconds, merge with the shadows and become invisible for 6 seconds.

W - manipulate shadows to trap and root an enemy for 2 seconds and deal 100/150/200/250/300 (+40% ap) magic damage. Root is increased by 1 second to targets with reduced vision.

E - channel your energy for 2 seconds and teleport up to 700 units, Leaves a dense fog (fog of war) at where you were standing and reduces enemy's vision by 90% for 5 seconds, deals AOE damage to an area of 350 units and deals 50/100/120/175/220 (+60% ap) magic damage.

R - channel your energy for 3 seconds and turn all allies invisible for 3 seconds and grant them 12% move speed. (if interrupted 10% of the cooldown in refunded)

when I made this kit I was thinking like a support mage or possible top lane. Because I was thinking more support the kit has a lot of utility but lacks the damage of most mages. And although the abilities are pretty straightforward I just wanted to show some ways on how you could use these abilities.

His Q can be used to flank enemies and provides long enough stealth to cast E which would activate his passive to deal more damage, followed up by a W to root the enemy could prove to be a powerful combo.

His R could be used to set up a team fight or to help the team escape from a lost fight.

His E can be used to set up some extra fog of war which could hide allies or give less time to react to a ranged spell.

This is all I have for right now, but remember this is just a draft and any and all feedback would be appreciated. I would like to know what you think could be improved or what needs to be dialed back a notch.