Slitherine

Hello,
i have finished 3 campaigns but the last, war of the heros seems to be hard.
The Problem is , during the figths against the 2 dragoons i lost a lot of units.
After finishing the lair of abermenx i lost also many units and received not enough money to resurect my army.
Does anyon have a idea .The dragoons are so strong, its difficult not to lose units.
Another question ,which file in the game i have to save to have after reinstalling the game al campaigns at my disposal ?
Thanks for help

One thing that really helps is to clear out an enemy village. This will tempt the dragon to fly over eventually. When it flies over there, freeze it using the hero elf skill (3 turns immobile) and hit it with every ranged attack and spell you have available on that round. then repeat the 2nd round, and the third round hit it with everything ranged then follow with the strongest melee attackers you have(Must have very high defense) and the dragon is dead meat. Sometimes putting the hero dwarf in the town works good too since the dragon will be attacking 3x defense with town and dwarf skills stacking, which hurts the dragon even more.