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

Well, Deleb won, and Frida appeared with Duncan, but a new problem arose. Frida turned out to be very weak, level 20, without armor, and without Divine Vengeance. And she loses the battle. It's possible to stop her (version 3.0), transfer everything to Duncan (he's level 24), but he also loses. And if Frida manages to get out, there's no way back.

Question: which campaign should I replay with Frida to level her up?

Added 3 minutes later