"Escape to Salvation" - "Magnificent Retreat" [Campaign 4, Mission 4]

I have no idea how to beat this battle on "Hero" difficulty...

I completed the entire campaign on "Hero" difficulty and it was fine. The battle against Kujin is actually quite easy, especially if she had a ballista (I was leveling up fire skills), it would have been even easier. In this battle, "Wrath of the Horde" definitely ruled; almost all the devils fell to it, and the hounds also suffered.