So about Zilean... [Rework Idea]

I picked up zilean a while ago and played him nonstop. I stopped suddenly because I didn't want to screw over my AD Carry. Even after his passive rework, he still feels a bit empty and feels like he needs more utility so that he won't be as subpar in comparison to the rest of the supports. For example, his double-bomb stun. It's a great AoE, and essentially you're hitting a nami bubble twice. But there are so many supports who can just do it better. Nami only has to hit one bubble, Annie with her ability to stun point and click, etc. Additionally, his W, Rewind, feels very lackluster, like a hit-or-miss ability.

Here are some of my ideas to change Zilean:

Passive- Time in a Bottle Basically unchanged. If I had to want something more aggressive, I'd probably choose something like this: Potential Passive- Chrono Flux Zilean's auto attacks deal an additional 30 + (5 times [Zilean's current level] ) + (30% of enemy's missing health) magic damage for 7 (+ 1 for [Zilean's current level]) whenever all no ultimate abilities are on cooldown.

Cooldown on Passive: 25-30 seconds.

Thoughts: It'd definitely be nice if this were to be his passive. When he spams his combo, the only thing left are your auto attacks, and it would definitely be forgiving if you miss your double-bomb combo, but in order to counteract that, the cool down on this would be pretty long. However, his current passive is a great way to help your AD Carry in solo queue, especially when behind.

Q- Time Bomb, essentially unchanged

Thoughts: High base damages and low AP scaling so to help with his "aggressive" support style.

W- Rewind, modified. Refreshes Zilean's and allies abilities (including ultimate abilities) by 3/4/5/6/7 seconds.

At max rank, this additionally refreshes ultimate ability cool downs by 75%.

Cooldown: 22 seconds at all ranks.

Thoughts: I feel like this would help him out a lot. During team fights, you have a great advantage, especially if you have a "non-ultimate" champion, (what I mean by this: Karma, Diana, etc.) Since Zilean doesn't really have a passive in the later levels, this would definitely help out a lot.

E- Time Warp, Modified. Zilean slows or speeds up an enemy or ally champion respectively, slowing/speeding their for 25%/35%/55%/75%/99% for 2.75 seconds, additionally dealing 10/20/30/40/50 + (30% of AP) true damage for 3 seconds to enemies.

Additionally, if a time bomb detonates while this ability is still active on that champion, all enemies in the area around it are stunned for 1/1.25/1.75/2/2.25 seconds.

Thoughts: Time Warp at the moment feels very fluid and easy to use but is hindered by it's duration. Give the slow/speed up a longer duration, and give it a longer cool down because of its additional passive. Speaking of that, I think adding it including the damage will reward Zilean players for landing double time bombs and will make them think about the timing of all of their abilities. This ability's range should definitely be nerfed though.

R- Chronodysplasia/Chronoshift

Passive: when allies around Zilean reach below 35% health, Zilean gains 30 +10x(Zilean's level) + 0.5 (% of missing health of allies) x (per ally) ability power.

TL;dr, the when Zilean's allies reach low health, Zilean gains additional ability power based on their missing % of health.

Active: unchanged, except this passive can only be activated if this ult is on cooldown