[That's because they didn't expect this attack. The Chimaeric Demons are keeping them occupied, and your attack appeared to target their commander. They would have never allowed you to do this damage. Look at how many barrier masters are there!]
Erik watched below. There were many of them. In fact, the number of shields protecting the blackguards from harm was astronomical. At that point, the battlefield changed. The undead had taken the front, while the blackguards went to the back of the formation.
That was also why Erik killed more blackguards rather than undead. But that wasn't necessarily good, because the undead Chimaeric Demons were still fighting, and they were the real problem.
Regardless, for a moment, it looked like Erik's gambit worked because the clones got a little bit of respite.