Zilean Rework idea-- Pure Support

First and foremost, his lore doesn't work for a playable character. He is, and I quote, "unable to impact the events which unfold." You shouldn't be able to play him if that's the case. Needs to be adjusted. Second, and second most important, let it be noted that his bombs have no relation to his lore, even the first two iterations. They'd need to be included and he'd need to be given additional damaging abilities to be a coherent character based around the bombs.

But that's not the direction I hope they go. I think his concept as a time manipulator would work best as a lower damage, higher utility support. Healing allies by reversing time on their wounds, similar to what his ulimate already does.

I will go over my suggested changes as well as an explanation for the magnitude and theme of the change.

Passive -- Oversight Starting after 6 minutes in, Zilean can click his map to lift the fog of war for two seconds. Zilean's allies do not share this vision. Cooldown 160--120--90, reducing at levels 6 and 11. As it is, the ability to share experience with an ally just doesn't have an impact. If it were powerful enough to actually effect the lane phase, then he'd be picked far more, especially in professional play. But very few champions benefit from a level up eight minutes into the game, when they're already near the next level and everyone besides Zilean himself is already level 6. While it does fit the idea that he has more experience than everyone else and is able to capture moments to teach others, I feel like the ability to see all locations on the map as if he had chosen to walk there in the present moment works just as well.

Q -- Reversal Zilean marks a champion for 4 seconds. Any damage a marked ally takes within that time frame is converted into grey health, and they heal for 20% to 50% (with an AP scaling) of the amount over the next 4 seconds (Allies also marked with Chronoshift heal additionally for all remaining grey health when they're revived). Marked enemies take magic damage at the end of the duration equal to one of his current bomb's plus the total of all healing they received during the duration. As I mentioned, the bombs don't really fit into his theme at all. And having only one difficult-to-use-even-with-practice damaging ability doesn't make for a coherent champion. I figured the idea of giving him an actual sustaining heal as a time-reversal of damage would fit well, and coincide with keeping his ultimate the same. Similarly, if he can undo damage I think he should also be able to undo healing.

W -- Particle Deceleration [Ground-target circle] Zilean halts the motion of all air in an area for 2 seconds, silencing all enemies within it. (blind, not nearsight) Firstly, I think having his Q/E cooldowns and Q's stun set in such a way that he actually needs to reduce them by 10 seconds to even be useful is frankly ridiculous. The gimmick that it "rewinds" his cooldowns isn't enough to validate weakening his other abilities below a normal level of usefulness. When thinking about an ability fitting for a character with limited control over time, it occurred to me that he doesn't have to directly effect enemies to apply crowd control. And a zone that provides a silence would work well with keeping his E nearly the same.

E -- Time Warp Essentially the same, but without the ridiculously long Rewind-reliant cooldown. Perhaps 8 seconds at all ranks instead of the current 15.
This ability fits the theme and would work well with my suggestion for his W. The only issue is the high cooldown.

R -- Chronoshift Also essentially the same, but I'd like to add a 0.5s or 1s stunning explosion to the revival of the ally. Sort of like a terminator-style bubble, giving the ally a moment to get their bearings after a teamfight revival instead of being immediately re-killed.