Zilean New Passive Idea
So my original idea was going to replace his passive entirely, but instead grant more of a hybrid of a double passive so that he has a passive for his level 18 but not take away the unique EXP aura that he has so what is going to happen is as Zilean gains levels one passive decreases in power as the other passive increases in power. And something I am going to focus highly on is the mage-support that Zilean is.
Heightened Learning (Passive): Range: 1500 units Zilean and nearby ally champions gain 9.5%(-0.5% per champion level)[9% level 1, 0% level 18] bonus increase experience points.
Zilean and nearby ally champions deal 10(+5
levels 1-6; +10levels 7-11; +15levels 12-15; +20level 16; +30level 17; +60level 18)(+70%AP) bonus magic damage on their basic attacks to slowed or stunned enemies, half damage if the target is not currently affected by one of Zilean's bombs. The same unit can only take this magic damage once every 10 seconds, but can be reduced whenever Zilean uses Rewind as long as the target is within range of Zilean.
EDIT: Okay, okay, made another mechanic to this where if the slowed or stunned target being attacked is NOT currently affected with one of Zilean's bombs [Time Warp slow or Time Bomb countdown] then the target takes half of the damage with the same unit static cooldown being the same. 70% Ability Power instead of 50% Ability Power.
Another change where the cooldown on targets is now 10 from 4 seconds but gets reduced if the affected targets are within the aura range when Zilean uses Rewind for even more cohesion with his kit.
Damage lowered and changed the scaling values so a lot weaker early scaling and dramatic increases in damage in the last few levels especially to 18 from 17 totaling 260(+70%AP) from 360(+70%AP).
uses a bomb and then your team gets 720 to 1800 free damage. That should only happen if he decides he wants to build a lot of AP, then he will provide the damage, but at the expense of him being so squishy.