Yuumi will be added to the Public Beta Environment for the patch 9.10 cycle and will move to the live version with the rest of patch 9.10 and features the following abilities:
Passive: Bop ‘N’ Block: random Yuumi attacks restore mana and grants her a shield that can be extended to allies.
Prowling Projectile (Q): A missile that deals magical damage to the first enemy with bonus damage based on how long it is in flight.
You and Me! (W): Passive ability grants Yuumi and her ally a percentage of each other’s AD or AP converted to Adaptive Force. The active ability allows Yuumi to dash to an ally champion and attach to them. If attached, Yuumi follows the ally’s movement and is untargetable by everything except tower damage.
Zoomies (E): Yuumi heals and gains a burst of movement speed. Shares ability when attached to ally.
Final Chapter (R): Yuumi launches waves of magic damage that root enemies after multiple hits. While using her ultra, Yuumi can move, attach to ally champions, and heal.
These abilities are on full display in a recent Chinese live stream video where the players take Yuumi and Twitch into the bot lane to face off against a Vayne and Soraka.