Alright ! As you can see, a plasma ball is floating around the level, and a green energy wall is blocking the way. In order to open it, you have to activate the red switch located onto the right. The green switch is the plasma ball respawn point, in case you accidentaly throw it out of the map. To open the energy wall, try to teleport the palsma ball on the red switch ... and, by the way, don't ever try to face the plasma ball, or you'll get a little surprise ... 