Well the biggest thing right now is that his name really does give him power, so don't ever say it out loud. I think most people call him Mally, but I've been using "Never-Speak-His-Name" since before I heard other people call him Mally, and it's sort of stuck for me. Pick a name and stick with it.

As for what he is... He's apparently some kind of creature hell bent on destruction. Of everything. Apparently he's been trying to destroy this world for a while, and apparently every time they beat him down he comes back again with a different form. The Kedan hope we can be the ones to finally stop him.