So I was trying out Arcade Kai'sa on PBE, and I checked out her evolve animation. I loved the sound that it makes, but it kind of seemed like it was missing something. I was thinking of a "LEVEL UP" text and sound effect when Kai'Sa evolved similar to Arcade Riven's death animation. It'd match the theme considering it's Arcade, so it would be perfect!
(an example, but Riot could make it 100x better)