The chained champion shown in the August roadmap. Just from the single image I wonder if they are even human or if it’s a monster. I wonder why they are locked up and where they are locked up in? Targon? Blessed Isles? Demacia? How mysterious.
I don't believe it will be Targon or the Shadow/Blessed Isles. First of all, the monks of the Blessed Isles didn't really practice imprisonment. Thresh's runic warlock is an exception of course, because he embedded the ancient, dark magic directly in his flesh and thus couldn't be allowed free to share that magic with others. The monks were generally peaceful protectors of the world by safekeeping ancient evil magics, they didn't imprison people because their society doesn't generally have a lot of disorder or war like Demacia or Noxus does, so I don't know why people keep thinking that a prisoner might hail from the Blessed Isles.
From a design standpoint, that prison and the chain design aren't Targonian - they utilize far too bright of a stone with smoother, crisper edges and polished surfaces, and the chains are very angular and geometric, which are design elements Targon doesn't favor.
It makes the most sense for it to be Demacian, considering it's been a LONG time since our last Demacian, and there's been surprisingly little lore from the region.
The colour theme of the picture reads Demacia, guess the champion is locked up there. Probably either a monster or a magician, who Demacians didn't want to kill for some reason.
Personally, I am not really excited for any of these 2 releases. Hope next year will have more interesting champions for me. =/
Chained champ is probably Morgana. She's in Demacia but is inherently wholly magic. She's chained up in Demacia.
There was a guy who did a whole post about this. HE was saying it could be some general of noxus or w/e. I'm terrible when it comes to lure. I think it's like katarina's father? And he would be imprisoned because of some political affair between noxus and demacia. I'll try and find the post and edit this one :)
Edit: Here it is: https://boards.na.leagueoflegends.com/en/c/story-art/WtTBkElB-why-i-think-general-ducouteau-is-alive-and-will-come-soon
Either a powerful mage locked up Demacia that is now free or 
s daddy
