A Giant red Psion with spikes sticking out of it. The boss has 4 machines that constantly replenish his shields. You can't do any damage to him until you to destroy these 4 machines. After doing enough damage, he will spawn 4 Psion's who will shield him constantly. This is when enemies start spawning in as well. You have to kill these Major Psions in order to start doing damage again. After they are dead and you do enough damage to him, the boss will make his own Void shield. The difference is that this one does not replenish. After you destroy his shield you can shoot the boss and kill him.