Rhez'Kham, the Void Jumper

Rhez'Kham is one of my more incomplete concepts that I have come up with, so there aren't any cooldowns or mana costs in the works at the moment. If anyone looking would feel like throwing some ideas out there for them, it would be incredibly appreciated. Also, some of the damage/distance/buff values will probably be a bit too heavy, so throw that criticism out there too. Thanks!

Abilities > Passive: Jumper - Each successive spell cast within 5 seconds of each other reduces the next spells mana cost by 10%, stacking up to 5 times. Hidden Passive: After casting a spell, all other spells go on a 1 second cooldown.

>Q: Aggressor - Teleports to a target location and grants allies 25% increased attack speed for 3 seconds and inflicts a 15/20/25/30/35% slow for 1/1.5/2/2.5/3 seconds.

>W: Sentry - Teleports to an ally, granting them a shield for 5 seconds at 10/15/20/25/30% max health and 5/10/15/20/25% Rhez’Kahm’s AP. Rhez’Kahm is stuck to the ally he jumped to, and after the five seconds are up Rhez’Kahm jumps up to 500 units away and roars, stunning all enemies in a small radius for .5/1/1.5/2/2 seconds

>E: Medic - Teleports to a location and gives all allied Champions 30/50/70/90/110 (+ 10/20/25/30/40% AP) health and 20/40/60/80/100 (+5/10/15/20/25% AP) mana.

>R: Essence of the Void - Gives all allied champions within 4000 units a single charge, used on next movement command. This charge allows the allied champion to jump up to 1250 units away, granting a 25/30/40% movement speed buff for 4 seconds on arrival. This charge expires after 10 seconds if unused