What? Do you have someone to put on level 4? Or how? Personally, I had the idea to put mummies on level 4.
You can put mummies on level 2, just give them a little buff, but vampires are really annoying, they always get taken out and don't have time to do anything. You need some good wolves, level 4, with a hero that has a splitting skill, for example, like the wolves.
Added 2 minutes later
What? Do you have someone to put on level 4? Or how? Personally, I had the idea to put mummies on level 4.