Well, in the Shadow Isles, there was the ruination, which would explain the wasteland we are seeing.
On top the mist I mentioned, which is the trademark of the Shadow Isles.
https://i.imgur.com/iLLP1sB.png
Look at the glowing symbol on the floor. It resembles (like I mentioned) what the mist lady has on her forehead in the crest.
https://vignette.wikia.nocookie.net/leagueoflegends/images/1/11/Shadow_Isles_Crest.png/revision/latest?cb=20161117061207
And another hint (at least I see it that way), is the name of the path: Sorcery.
Look at the other names. They all have a name that kinda represents the region.
Precision - Demacia: Demacia is the most disciplined nation in the game. The runes use alot of hero symbols.
Domination - Noxus: Noxus actually tries to dominate the world by force. Strength is all for them. The runes have alot of savage symbols.
Resolve - Freljord: The Freljord is a hard land, you have to be hard yourself to survive there. It is a wild land, fitting for it the runes use alot of nature based symbols.
Inspiration - Mount Targon: Inspiration in my opinion fits, the aspects of Mount Targon are leading figures and inspire their followers. Partly there are Piltover related runes, but some of them use the celestial theme of Mount Targon.
What's left is Sorcery. I don't know how you feel about it, but I wouldn't relate the word "sorcery" to the void in any way. Meanwhile it seems fitting for the Shadow Isles, most champions from there are magical beings by nature (ghosts). The symbols are using magical items (Shadow Isles are known for magical artefacts), such as the manaflow band, the ultimate hat and so on. The runes in general have a magic heavy influence, the main theme of the Void is actually "bio weapons, evolution and consume".
I respect your opinion that you think it is supposed to be Icathia, but I am extremely confident myself that Sorcery is indeed located in the Shadow Isles.