Riot Games released patch notes for the upcoming update 13.4. Veigar, Orianna, and the recently updated Ahri were buffed among other champions. Amumu, Jarvan IV, Samira and others received nerfs. The changes appeared on Matt "Prhoxzon" Leung-Harrison's Twitter.
In the patch preview, the developers also wanted to buff Kennen but removed him from the list.
The main theme of the patch was balancing ranged vs melee supports in the bot lane and adjusting early snowballing. Another developer, Phlox, elaborated on the latter, explaining the new Kill Experience in a separate post.
Patch 13.4 will come out on February 23. Probably, we will learn about the next champion Milio during or right after its release. As Riot Games recently teased the new enchanter from Ixtal on the PBE server, we can assume it will arrive with the update 13.5.