Source for the images is the Chinese LoL site lol.qq - a similar announcement does not yet exist on the other regional LoL websites, it is only on lol.qq atm so you will have to wait for additional specifics and details.
Here are the two images (similar image, different text) from the Chinese announcement page:
[For those who are doubtful, this image includes the name Maokai.]
As a reminder, the VICTORIOUS skin is a reward for players who place in gold or above during the current ranked season. While we do not have an end day for 2016 season yet, typically the player ranked season concludes in early to mid November after the World Championship wraps up.