There are numerous types of champion updates in League of Legends. These updates affect a character's gameplay, or focuses on their artwork and visuals.
Visual and Gameplay Updates (VGU) will modernize the artwork and animations of a champion, while simultaneously updating their abilities. An example of an upcoming VGU is Skarner, who won a vote to acquire the update over other characters. Meanwhile, Comprehensive Gameplay Updates (CGU) are utilized to completely rework abilities for underperforming champions. Aurelion Sol has been one of the lowest played characters over the years, so Riot Games opted to give him a CGU.
There is one more update called an Art and Sustainability Update (ASU), but what does that entail?
What is a League of Legends ASU?
A League of Legends ASU was created by Riot to ease the skin development process for certain champions. ASU's are typically used on characters that have been released a long time ago and need assistance in meeting the updated artwork standards.
Caitlyn received an ASU at the end of 2021, which increased the quality of all her skins and gave her skins new splash artwork. Riot announced an Ahri ASU in 2022, and it will finally be released in a couple of patches. This will make one of the most popular League of Legends characters much more visually appealing than previously.