The folks over on reddit have opened their 2014 time capsule - a collection of information on the LoL happenings from this time last year published to reflect back on now that a year is past. This time capsule post mentions the notorious Ao Shin, a storm dragon concept that was previewed way back in 2013 as an upcoming champion but yet to come to fruition .
In the discussion of what happened to cause such a delay between Ao Shin's original preview and his assumed future release somewhere down the road, ZenonTheStoic stepped in to clarify:
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They said that the champion is super difficult to create, and they don't want to release him too quick like they did with Azir. They said his kit is not the usual and its extremely difficult to make it work.
We don't have a kit. We had a number of kits we were trying back in the day, but none of them worked out. This is completely normal for a champion (both Azir and Lucian had a number of kits previous to me starting work on them that didn't work out; my first kits for them also got scrapped, including Lucian's infamous homing missile ult and Azir's "just summon 7 fully controllable soldiers" ult). Game design is a highly iterative process. The only mistake we made with Ao Shin was that we talked about him way too early in that process, when we weren't yet sure how close to done we were.
As for Azir, the additional time we would have needed on him was toward the end, when you polish and fix bugs. That's very different."
When asked if there is an expected time frame for Ao Shin, ZenonTheStoic replied:
"We have absolutely no idea. Definitely not any time soon. I would not put money on it being this year."
[UPDATE] In a follow up thread on the topic of Ao Shin, ZenonTheStoic reiterated:
[1] "This... isn't news? Meddler posted the exact same thing 5 months ago on our forums:[link]"
[2] "That was a coincidence. Look, guys, we announced a cool concept too early. We're not even sure he's going to be called Ao Shin at this point--maybe that isn't the best name for the concept? We got a bunch of people ideating on what to do with the champion, but there's no kit, no uptodate concept art, nothing at the moment. Curb your enthusiasm: there's a really good chance you won't see this champ this year.