If you have all champions and are stupid enough to go "Hmm, I wonder what will happen" and reroll them, it's really just a random champion permanent that then lingers in your crafting inventory to always remind you of your own stupidity.
And now, one year later, that is still not fixed.
Tried rerolling 3 random champion shards into Xayah / Rakan moments before their release...
Rerolling
Reroll three similar types of loot into permanent loot of the same type (for example, reroll three different champion shards into a permanent champion guaranteed not to be a duplicate of one you own).
http://na.leagueoflegends.com/en/site/2016-season-update/champion-mastery.html
Support gave me a load of their usual rubbish, taking 0 responsibility for flaws with the client, and even had the audacity to claim there was nothing they could do.
Well, at least they are right there - there really IS nothing they are good for.
There was no error message to give in fact. Players are actually able to reroll shards if they want to, for whatever reason, even if they own all champions already. The reason you didn't get any of the new champions was because they were not available yet, but the rerolls still count and as such you get a random champion shard if you already own every other champion.
It does specify that rerolls give you a piece of content you don't own, but only if the new content is available in the store, Champions/skins that are not yet for purchase in the store can't be obtained through Hextech even if we know that they are in the game files. Players have to wait till we activate them. Just because the champions appear in "My Collection" that doesn't mean that they are yet available for use. We typically wait a bit before activating new content to make sure the patch itself is running smoothly. Also something to keep in mind that is present on the Hextech Crafting page:
"CAN I EARN CONTENT THAT JUST GOT ADDED TO THE STORE?
Yes! However, it takes a bit for new content to get added to the Hextech system, so we recommend waiting at least a day after a new item hits the store before trying to roll for anything new."
So always be careful even when they are added to the store as the Hextech can update a bit more slowly at times. I'm sorry that you went and rerolled so early when they were not yet active in the store, but there is nothing we can do. We post in the news when new champions/skins become available and even in the patch notes we specified "Xayah, the Rebel, and Rakan, the Charmer, will be released later on during patch 7.8!", so always check the store before making any Hextech actions. Really wish you didn't use the shards so early, but at least you still got to play both of them in the end.
However adding a warning to the player might not be a bad idea in case he already owns all content. I recommend posting the idea on the Boards.
(Riot Games Player Support)
As if an error about "all content already owned" or similar error was not something they could damn well have implemented long ago.
-teed to be something you do not currently own
