I can count on one hand which armies I have lost from beginning to end. I thought more challenges would come and I have time to complete sidequests later, but the first mission was over before I had explored the complete map with drones only. I did not stop once to wait for new units, I just took what I could produce on the way. I did take the first city in the first (or second) turn, did only some basic exploring and then marched directly from enemy city to city. I cannot think of a scenario where I could carry the same unit from start to end.they were dying like flies while my heroes cut through leaders and monsters. This provided me with much needed strong heroes ( I did defeat Sunken Cities with only two heroes, gaining nice octopuses on the way). Later I did send her without an army but another hero flying on wyverns all around the map while my main army was progressing very slowly, often loosing cites. I found it quite difficult at some times and I had the feeling that I had to level my heroes up as high as possible to stand a chance, So I did send her at the beginning with an army to explore and fight. So I invested 86 hours for the Elven campaign and loved every minute of it :)