It was fun but the fourth undead army on the beach forced me to stop playing Soothsayer and start a new impossible game as Viking. I simply cannot beat an army of 20k skeleton archers, 800 ghosts, 600 ancient vampires and 26 bone dragons.
I've run out of units that can summon, I have no access to demonologists, royal griffs, rune mages or royal thorns and one stack of 10k skeleton archers kills 1/3 of my paladins just with that black arrow (and they keep one hitting phoenix at melee). I am able to kill about 4-5k archers before my whole army falls to vampires, dragons and ghosts.
I will keep my save in case someone here comes with any idea how to beat this fight (no matter what the loses are), because I don't see any option now.
EDIT: Oh, how sweet the evil book bug was QQ