A special golden chroma of the Championship Ashe skin has made its way onto the Public Beta Environment and you’ll only be able to get the chroma skin through a special World Championship crafting event.
Riot DontHassleDaHoff posted on the forums explaining a bit about the skin (and the ward skin) that will be crafting exclusives.
Hello everyone! You’ll see on PBE soon the Championship Ashe Golden Chroma and the 2017 Golden Championship Ward. These two items can be unlocked together via the 2017 Worlds Crafting store for 320 Tokens. These items will only be available via the Tokens you can earn during Worlds. At the end of Worlds, we’ll be removing these from crafting.
So these two will be items that you can get through tokens. There’s no word on the event yet, but we can probably expect something kind of similar to the Omega Squad event, where you can complete missions in exchange for tokens to be crafted into loot.
You’ll need quite a few tokens to unlock the chroma and ward skin, but they’ll both be proof that you were around for Worlds 2017 as a special way to commemorate the event.