With heroes that depends on normal attacks like Illidan or Assassin you can buy Inmortal(Golden armor) and Mugen that should be enough against Hidra, them for Vampire Lord you can have one more Legendary item and a Katar that is very cheap that way do not miss so much or a strong tower the Guillermo Tell tower is very effective agaisnt this Vampire cause it does not miss. This red lyrics bosses Brodmother, Hidra, Vampire Lord, Nosferatu, etc come only for one line means that if you play with a team this bosses will be a lot easier.