What is Satan Doing Here?

Well if you really want to know... There was a flux in the space-time continuum which caused the chain of event that led Satan to Hell to break. This created a wormhole that sucked only Satan up, and closed up shortly after. The wormhole led to this exact spot. Now he is trapped in a tiny, prison

Or it could be the artist trying to add a little humor into the game.

It's the latter, but hey, it's good to have a little imagination. xD

I had a navigate a maze to get this far, and just past Satan was a large pile of gold. I'm not quite sure why the developers chose 'Satan' over anything else, but as far as I can tell, this is just a random thing put in at the end of the extremely challenging maze of rock, just before a large vein of Gold. Maybe it's his personal stash?