You enter an area with blue glass globes on a maya construction. I'm a bit unsure if this really belongs to the bossfight as well or not. But since he appears already there i would call it stage one. While enemies attack you he repeats setting the ground on your position on fire. He spawns around to certain points in this stage. As you can shoot him, i don't think it is the plan here cause i did it as follows: enlight all enemies as usuall or entrap them into those fire spots while you wait till they head towars you, enlight them to force them to stop, run away and they will mostly burn to death. Enemies spawn not unlimited. So kill em all and concentrate on the riddle later. After you did that, enlight the globes with the blue glass balls behind the statues. The light has to hit the globes, so timing is asked. After you did that you enter stage two: now the boss appears to fight you. It's easier than stage one i think. Hold the light towards him and shoot him till he disappears. Rinse and repeat a few times. You finally made it. Congrats!