Mad Scientist Gnar
https://www.pinterest.com/pin/727542514773538686/?lp=true
Gnar is perfect for a Dr. Jekyll and Mr Hyde skin. Call it Mad Scientist and push it out. I know Riot does skins that sell, but I feel like Gnar is one of those universal fan favorites. I'm not entirely sure what his abilities would be, but I'm sure you could make something work. His recall could be him as mini gnar holding up a vial and doing an evil laugh, drinking it, and Mega Gnar attempts to break free (like the hulk halfway emerging from banner) and Mini Gnar keeps control and laughs again, then burps or hiccups or something from the potion.
"Exactly who do you think you're talking to?" (Interaction) "I'd like for you to Hyde so I can Jekyll." (Taunt) "I put the vile in violent" (Joke)