Sry man, i saw your post as soon as you started it, but i lost all my old saves when reinstaled game and started redsdands campaing so i have no end game save with all 93 quests (but i did it couple times, so it`s not bug).
It doesnt give you anything special, only on end score you see number 93quest, nothing more. Instead wasting nerves to it, try different combo`s unit/hero/build and have fun
