Void based support champion Concept

After a couple years of tweaking i've come up with this champion concept on the first support based void champion. Although i don't have any sure design for his looks, (something like a leech or some form of draining creature), I have thought of his spells, stats and name Osh'Rai and as such this is going to be a little lengthy so please bare with me.

Base Stats

Health - 420(+89 per level)
Health Regan - 6(+0.7 per level) Mana - 300(+24 per level)
Mana Regan - 7(+0.5 per level) Attack Damage - 50(+2.65 per level)
Armor - 12(+1% HP)(+1.5 per level) Attack Speed - 0.625(+0.0245 per level)
Magic Resist - 30(+0 per level) Movement Speed - 330(+0 per level)

Passive - Blood Armor 1% of maximum HP applied to armor

Q - Void Blast Cost: 60/70/80/90/100 mana Base Cool Down: 12/10.5/9/7.5/6 seconds Range: 750 Description: Fires a ball of void energy in targeted direction dealing 60/100/140/180/220(+75% of Ability Power) that explodes on champion or minion impact dealing 50% reduced damage in a 200 unit radius around first target hit (100 damage max vs. minions). Additionally it reduces the movement speed of the first target hit by 10/15/25/40/60% for 3 seconds.

W - Void Drain Cost: 75/75/75/75/75 Base Cool Down: 15/13.5/12/10.5/9 Range: 650 Description: Launches a tether in targeted direction dealing 80/110/140/170/200(+65% of Ability Power) over 4 seconds. This Ability can be activated a second time after the 4 second drain (for 10 seconds) to restore 30% of the damage dealt to all allies in a 400 unit radius around Osh'Rai( If no allies are in range, activating this move a second time doubles the percent healed to Osh'Rai.)

E - Void Tether Cost: 20% of Current HP Base Cool Down: 15/13.5/12/10.5/9 Range: 600 Description: Passive - Tethers to the closest ally champion in a 600 unit radius for at least 4 seconds and gives that champion 5/7.5/10/12.5/15(+15% of Armor) to armor and 2/4/6/8/10(+10% of Magic Resist) to magic resist

Active - returns the health cost as HP to tethered ally over 4 seconds. While active Void Tether cannot select a new ally champion

R - Void Armor Cost: 150/150/150 Base Cool Down: 120/90/60 Range:N/A Description: Osh'Rai strengthens Void Tether, increasing it's range by 150 units and having Osh'Rai take 50% of the Damage Dealt to tethered ally for 2/4/6 seconds. while active Osh'Rai loses his Armor And Magic Resist bonuses for Void Tether.

Well that's about it for my idea for a void based support champion, any helpful comments or suggestions on how to better balance him will be appreciated.