This one is difficult so here's the best way to beat him. He has shield so you will want to bring an electric weapon to remove it really fast, once that's gone you will be able to remove health so try your best to head shot as much as you can. After the shield is broken there will be some time that you can remove his health til he goes back to his spawn to recharge, again make sure you use an electric weapon on shield. Now onto the attacks, he cycles through a few attacks that are easy to avoid with good timing and the shift move. Now onto the "rounds", when he goes back to his spawn to recharge enemy's will spawn from the right and left so make sure you avoid/kill them. They are really low health but can cost you the game if you aren't careful