Much like last time, you should shield bash him whenever he attacks. While he is stunned, you can use thrusts to attack him, although I found that vertical slices, which are easier to do than thrusts, are also more easily usable.
After almost knocking him off, he’ll lose his electric weapon and the gate will move closer to you – as before, don’t touch it or you’ll get hurt. Knock him off almost a second time and he’ll lose his left arm and the gate moves even closer. Repeat the process one last time to finish him.