Zilean rework ideas
First, I'd like to say that I do not believe he should be pigeon-holed into support. There are a lot more interesting things you can do with a wise, old chronomancer that could make him similar to how Lux, Orianna, or Morgana turned out.
As a character, he would catch people's interest, thematically, if all of his quotes revolved around time and existentialism, specifically showing him to be jaded. If you want to keep his humor, you could give them a much darker theme to make him a lot more interesting overall. This meshes very will with him being jaded too. Visually, I think a jaded suits him well, similar to Nasus. Lastly on this point, when I hear his voice, I don't think wise/experienced. I think frail. I think crippled mentor. Even with his 'wise' quotes, it just doesn't feel like what he should be, similar to Sion pre-rework. His lastest art direction from Riot makes this even clearer. The splash simply doesn't match up.
Anyway, on to the kit:
**Passive: Zileans non-ultimate abilities hold extra charges. He may select a new ability to hold charges at 6/11/16. Abilities may be selected more than one time. **
Same concept as Katarina's W rework way back in the day. Lacking an entire spell severely gimps a champion. This allows him to repeat abilities still, but he's limited to the ones he selects at each benchmark to prevent him from being over-bearing early game while allowing him to do more late game, where Zilean has suffered most since conception. Allowing an ability to be selected more than once makes it so his end-game goals between different games can be as varied as Kha'Zix was intended, but much, much more dynamic. Tweaks can obviously be made, such as capping X ability at 2, increasing mana costs for repeated spells, increasing the CD for each consecutive cast, etc.
Q: This ability could hold the same concept, but I feel his abilities should have a stronger tie to time specifically, not a bomb. Time bomb is kind of just a gimmicky excuse for a time theme thrown on a support. In addition, as a support it can feel very counter-intuitive to use his Q to peel. If Riot refuses to make him something other than support, the rework should cater to a counter-engage style kit, since that is where his ult shines most and why I feel people should be picking Zilean. Not to mention that if Zilean is ever viable for an engage comp, he is nothing but oppressive because it ensures the enemy cannot fight back effectively before they are at a severe disadvantage.
W: Anything can go here. What goes here depends on whether Riot wants him to end up an interesting mage, or an interesting support. If supportive, it should probably go in the direction of a shield, possibly a similar concept to Tahm Kench's, but affecting all nearby allies (less than 400 units) and much less potent (capping at less than 20% of their max health). This could have some type of enemy interaction, but you're getting to CertainlyT-level overloaded abilities at that point.
E: Could remain the same, but it would be a lot more interesting to see something with a bit more interaction and "oomph." Possibly make it more of a 'time flux' theme. Have it slowly trade X/X/X/X/X movement speed (likely flat and before any reductions) for X/X/X/X/X seconds between your target and the closest enemy/ally (whichever you did not target). At the end, there could be damage based on how long enemies/allies were in range of your target before the effect finishes. If possible, only make it the first champion to enter its area of affect around your target to allow much more counter-play. This should not slow when cast on an enemy until an ally is in range of its AoE, nor should it speed up an ally before enemies are in range.
R: Likely the same. This is what people think of when they see Zilean. This is why people pick Zilean, strategically. While people are very familiar with the bombs, that is only because they are his only source of direct impact outside of his ult.
How do you think Zilean should be reworked/rethemed?
Comment below.