User blog comment:Emptylord/Blogs/Time-themed abilities/@comment-5514182-20131220064303/@comment-1330314-20131222010027

It's definitely a unique spell, but doesn't work as an active ability due to the above reasons. When I did my Zilean rework a little while ago, I moved it to his passive, allowing him to cast one basic ability on cooldown every few seconds. Onto your ability concepts:
 * Recursive Strike is completely unique for LoL, and looks like a far healthier version of Kunkka's X Marks the Spot from Dota. On the other hand, I'm not quite sure about the mobility: if it's intended to be an escape, it's going to conflict with the damage component, since typically you're going to be using it for one or the other. Its type of mobility also makes it predictable, meaning enemies will know where he'll be the moment he casts this and anticipate, which would also not make this good for escaping.
 * Chronospheres is a great idea for a support ability, offering both healing and a peel. However, I don't think healing is really part of Zilean's theme, even as a support, so this should probably be saved for a new support champion concept.
 * Reducing Time Warp's duration is a fantastic idea, and would prevent him from perma-slowing enemies. Not quite sure about the trail idea (which could potentially be very powerful and very messy in teamfights), but changing the ability's scaling from duration to slow intensity sounds great.
 * Spacetime Schism's knockback looks too brutal to be part of Zilean's kit, particularly as it doesn't really have any relation to his current abilities.
 * Spacetime Prison is effectively a projected Jarvan ult, in that it traps groups of enemies inside an enclosed area, which is massively strong. The space warp effect also sounds like it would confuse enemies trapped inside.
 * Rewind 1 looks like a fantastic idea for an ultimate, and fits with Zilean's theme perfectly. The only downside I see is that being able to use this only on himself would strip him of a lot of his supporting power (and he's already a sub-par support, even with the new gold flow).
 * Rewind 2's passive would give Zilean an overwhelming visual change, and the active doesn't have the preparation factor that Rewind 1 and his current ultimate have. Rewind 1 seems like the better of the two.
 * Twisted Time sounds like a replacement to Zilean's Time Bomb. Not fond of the healing, but the delayed bomb component looks nice.
 * Delay Doom is very similar to Kunkka's ultimate, Ghost Ship. Riot specifically cited this as an example of an ability that's confusing to read due to the delayed damage not providing clear and immediate feedback. A simple damage reduction would be clearer, but that wouldn't work with Zilean's theme.
 * Chronolock is an interesting ability, but its main problem is that to be fully effective Zilean would have to be in the middle of the enemy team, whereas Zilean's a poke champion that typically stays in his team's back line. Having enemies exit the chronolock upon being attacked also sends mixed messages, since you might be using this to hold a target down so that your team can swarm them, but then having them focus said target could give them a chance at escaping. If the lock duration is too long, then it would be overly unpleasant to endure for the enemy team. If it's short enough, it might as well be a channeled suppress, without the release upon attack conditional.