I figured that one out: you have to get the yellow glowing enemies to zap the pillar, then it lights up and opens the door. But...then later I thought I was going to fight the skull king and the game teleported me to a gray area with a throne in the center and the walls didn't work; I could just walk off the edges in all directions, and no skull king showed up and the display was all glitchy when I did walk off the edge.
