Near the end of the level you see two rows of the electrical towers with spotlights searching the ground. While avoiding them take out the soldiers and their commander (the towers don't care who they zap so use them to make quick work of it).You'll have to fight more soldiers- once they are gone the barrier will drop.
Past this point you will come up to a gate- smash it down. You'll be in a large area with steps leading to Cynder's fortress. Take out the electric cannons along with the soldiers and commander to face the Electric King.