What I did was, to do normal campain, with only monk or another healer, and no hitter heroes. No automatic attack. It did 1 or 2 shield activation per campain attack. So you must have stamina to do 15-30 normal campain attacks.
I did it in chapter 19-4 "friendship is magic" normal campain.
Add Expedition, FP and Coli attacks, for the quest. If you want it to do it faster.
I did it with no problem with a lot of stamina, it just takes time to do many normal campain attacks.