Which monster do you like the most in Heroes 5 (level 6)?

Huh... who are you talking about? Sorry, I didn't understand. Who is it that attacks the units standing behind?

Have you played the "Hammers of Fate" campaign? There, each improved human unit has an alternative version. For Paladins, it's the Knights of Isabel. Their ability is that if they move more than 2 squares, they attack the unit standing behind (like a dragon). It's also great because it doesn't work on counterattacks, and the opponent won't be able to use this ability against you.