I dont exactly have trouble with abyssals or chain maps. But they can be hard for some, so I thought of a Call for Reinforcements feature.
Like during any turn you can call for for 1 friend unit once during that map and that friend can fall in battle. But if they do fall they cannot be called agian for a day. I think it would be fun.
I would love to know my unit helped someone with a map they couldnt get through with what they had.