Summerfae
Now I've got that boss that hides in one of the five portraits. Major suckage. @_@
Here's a trick. Stand in the center, go into first person with the bow, and spin around. When one is coming, aim at him, but if he doesn't start to warp, and unless you're fast enough to shoot the real one, run to the edge to avoid the lightning that's fired.
After you beat this phase, he starts shooting projectiles at you. Swing your sword to knock them back at him. It's going to be a game of tennis but he eventually loses. That's when you run up to him and hit him.