Maokai and his release date were leaked from the March 2011 issue of the 'PC Gamer' magazine.
Champion Sneak Peek: Maokai, the Twisted Treant
By ByronicHero 
Sometimes, when you look at the League of Legends champion lineup, it's easy to feel like you've seen it all. You've seen light mages, thorn mages, mad scientists, illusionists, ninjas, and warriors with gigantic swords. But there's something that this next champion has that none of them do: roots. That's right, while you may have been engaged in epic, pitched battles with trolls, gargoyles, ogres, scarecrows, minotaurs, mummies, and mutant armadillos, I bet you've never had to fight a tree before! Introducing Maokai, the Twisted Treant; a groundbreaking new champion in the League of Legends whose bark may or may not be worse than his bite. You decide.
Champion Update: Maokai
By fizzNchips 
Maokai's the latest champ to go into the champion update workshop, and has come out the other end with some fancy new bark to wear on all of his skins!
Just like Singed, Maokai's rig was in a fairly good spot while the rest of his look was a bit... well... old. So we changed it up, updating his model, textures, spell effects, and a few of his animations on his base model and each of his skins!