As for the Vampire Lords, on another map, they were simply defeated due to their weakness. I attacked a gold mine with 8 units + 20 skeletons, led by a Necromancer hero of level 3-4. The mine was guarded by 7 Mages and 2 Archmages, I believe. The Lords were quickly wiped out, and only about 3 Mages perished. So, they need to be around 18 in number to represent a real force, and a hero with high attack and defense would also be desirable.
As for the Vampire Lords, on another map, they were simply defeated due to their weakness. I attacked a gold mine with 8 units + 20 skeletons, led by a Necromancer hero of level 3-4. The mine was guarded by 7 Mages and 2 Archmages, I believe. The Lords were quickly wiped out, and only about 3 Mages perished. So, they need to be around 18 in number to represent a real force, and a hero with high attack and defense would also be desirable.