if you're still stuck at first focus on taking all the land you can while killing the zombies inside your town. once there are no more free spaces focus on the zombie towns north with the knight girl at the front to prevent your troops from getting infected (since she can't be infected. Then just go down take out those zombie towns place down a few castles and wait until you have the money to take out all the necromaners in one turn. Be sure to be clearful about making 2 zombie knights in one turn.