Zilean Passive bug(?) and other feedback

Hi, I've been playing Zilean a fair bit the past couple of days, and I think I found a weird bug for his Passive.

"Zilean generates 2 / 3.5 / 5 / 6 / 12 experience every 5 seconds, which does not advance his own level. When he has enough to level up an allied champion and is out of combat in the last 10 seconds, he can right-click them to initiate a 1 second channel, after which he grants them enough experience to finish their level. Zilean receives the same amount. If the channel is interrupted, Time in a Bottle goes on cooldown for 2 seconds." (Taken from wiki)

The description clearly says that it is only usable when Zilean has been out of combat for 10 seconds,but sometimes, I can still use it after I double bombed a minion horde, Auto attacked and cs'd a minion, and some other time when I attack something the passive goes on a 2 second cooldown instead of the described 10 second cooldown. I've noticed it in a few of the Zilean games I've played, and while it's not that much of a noticeable difference, and is even beneficial to Zilean, it just feels kinda clunky and somewhat unpredictable.

Next I'd like to say that with the recent AP item changes, it's actually helped Zilean in my opinion. I used to play a lot of Zilean (got from Bronze to Silver 1 with mainly Zil mid last seasion), but after the new Season changes about half a year ago, I found him nerfed and more difficult to be relevant. Last season I used to rush Tear and then Athene's followed up with Lucidity for a quick 40% CDR (with the 5% from masteries) and infinite mana. Then I'd go some AP like Deathcap or survivability like Zhonyas, depending on the situation. That build allowed me to kill waves very efficiently due to the mana and CDR from items and was able to ramp up damage due to the high base damage and AP scaling. Then came the preseason changes and Lucidity boots got reduced to 10%, and the easy 5% from Masteries was gone, it created a roadblock from reaching 40% CDR. It felt like a big hit and I haven't played him as much. Now with the midseason changes, I'd still rush Tear, and then Rush Morellos and Lucidity. That gives all the mana I need, and also the 100AP from Morellos is also a big buff from the 60 AP from Athenes that it used to give. Next up I really like Protobelt on Zil because it gives the 10% CDR to cap, in addition to extra survivability and versatility and even damage!

Another thing I want to mention is how none of the Keystone Masteries seem to fit Zilean's playstyle well. Deathfire Touch has reduced effect, WindSpeaker only works for his ult, Stormrider is hard to proc; it seems like Thunderlord's is the only choice to go, and while it does help Zil's early game a bit, late game it's harder to make use of it in the way that other champions can. (Or maybe I'm just not skilled enough to weave in autos :P)

Finally, I'd like to talk about his skills, and in particular, his E. Overall, I'm pretty satisfied with Zilean's kit. He's able to deal a ton of damage, and has great utility and even a 5 sec AoE stun. The only thing that doesn't feel as satisfying is his E early game. The spell is on a 15 second cooldown at level 1, and it ONLY provides a speed buff. It honestly feels kinda lackluster, especially since the cooldown is not refreshed when you use W until you get enough CDR. Most other speed buffs from other champs not only have a lower cooldown, but also offers additional stats as well. But I dunno, maybe it's just a Zil thing and it's needed in order to keep him in like so he can't speed/slow 2 champs at the same time at just level 3. Late game once you get enough CDR, it's barely a noticeable difference anyway...

Oh and also, not sure if I remember correctly, but when he places Q and R on an ally, and they die, the Q doesn't explode?? Is that intended? Because I think it would be really cool if, say, there's a Kat chasing you while you're low HP and you run to tower and then R and Q yourself and then Kat W onto you into your tower. You live with R and the Q and tower kills Kat... (Similar scenario happened except I misjudged Kat's W range and didn't R in time :P)

Thanks for reading :D

Thoughts? Comments?