Yuumi remind me of Abathur from HOTS and it is very special to me
For the ones who don't know, Abathur is a champion in the game Heroes of the storm where he can "host" any of the other 4 playrs in his team and assist them with his spell. He can do it from anywhere in the map and also could create a copy of them.
Abathur was a very unique character, even for HOTS standing, and I always felt this kind of character couldn't translate in lol but I am SO SO glad that Yuumi take this kind of mechanic where you are attached to a player and boost them, or you can jump from them and be your own entity.
It allow for a lot of versatility and also skill expression, nothing feel better than properly switching between teammate during a teamfight to give them that crucial heal/shield/haste/slow that will create a good opportunity for them.
There will be a lot of potential issue with this champion if their number are too high but I am very definitely excited.