Tabu, the Voodoo Shaman was rumored to be a new champion, but is now considered cancelled.[1][2] Tabu may be based off of the DotA champion, Voljin, The Witch Doctor, and may have been reworked into what is now Swain.
On the 2010 Harrowing map, a coffin, (on the extreme lower right), can be seen containing him, along with Averdian and the Plant King. This could be interpreted as the "nail-in-the-coffin" confirming his cancellation. His name is a play on the word 'taboo'.