Max Ultra!
Diablo, Lux's First Born, watched the battle with a calm expression on his face.
All he wanted in life was to protect his Master, Lux, from harm and ensure that the latter would be able to do anything he wanted.
However, as he followed the red-headed teenager on his journey, the Death Knight understood that his current strength was not enough to protect Lux completely.
His ability to excel on large-scale battlefields was not due to his own strength, but because of the armor he was wearing. Diablo didn't mind this at first, but after the battle in the Gate of Conquest, as well as their current situation, he understood that what he could offer was no longer enough.
He was not the only one who felt this way.
Ishtar, Pazuzu, and Orion felt the same way he did.
They were Lux's first protectors, and they were very happy to serve and protect their Master, who was too kind for a Necromancer.