Which monster do you like the most in Heroes 5 (level 4)?

I don't know, for example, I don't consider succubi to be just a nice addition, but rather a core unit for the demon army, even before the Pit Lord appears (and even after). They can be used to clear out neutral creatures without losses, and even towards the end, they don't become weaker like many early-level units do. This is a rare unit that remains effective even in the late game. By the way, the same can be said about the new druids, while the riders are not as useful in the late game.