Paladin + Warrior= Win. Normal enemies: Stun all, earthquake, heal if needed, finishing special blow. Bosses just use their double strikes, heal, warrior special. Very simple hard badge.
Get the Orangutan and the big dwarf hero and the girl hero, then add whatever units. Hit assault right after your hero's spawn and crush the castle before the dragon appears on level 10. Almost no enemies are in your way. Easy 10k to get a titan for the last level.