Earlier today an anonymous Rioter, under the moniker of "Zaun Lab Bot", posted two images on the League of Legends forum.
The two images unveiled details of Riot's next concoction to drip onto the Fields of Justice. By looking closely, readers can see short passages regarding the next champ and what he/she/it exactly is. Judging from the various descriptions of "rapid growth" and "cell divison", it is evident that the next champ is some sort of shape-shifter.
Currently, the codename for the next champ is "Zaun Amorphous Combatant", or Zac for short. Other details included imply that "Zac" is capable of talking, and has a very unique and cute voice as described by the various experiments that were performed on him. Not to mention it seems that rapid growth will be incorporated into his skillset and that he can reach very large sizes.
Expect more to be heard about "Zac" in the coming weeks on the League of Legends forums.