User blog comment:Caporai/Mordred, the Wicked King/@comment-5110387-20121015145703/@comment-3286233-20121015163856

We hope so. I got an answer from RiotRaven, and he did state that there will be a demonic champion in the League:

http://na.leagueoflegends.com/board/showthread.php?t=2500837&highlight=demonic