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

3DogMZA: Well, converting one upgrade into another is very cheap. I don't remember how it's calculated... It seems like it's a certain percentage of their cost. And you rarely have to do it. Druids' Lightning deals more damage than Mages' Fireball because Fireball is an area-of-effect spell; it simply can't have high damage. The same goes for Succubi; they have a chain attack.
Loken: Chaos magic for the Elves is their second main magic, like Summoning for the Elves, meaning it appears quite often. As for the new Druids, I was completely blown away when I saw what they do. 80-something Druids give 18 spells! (This is the maximum they can give; increasing their numbers further doesn't give any bonus). Considering that you can cast spells on a ballista or a hero's arrow, you can do some amazing things... Three Earth Shocks at once, even a Dark Elf wouldn't dream of that. Or one on each cursed enemy. It will drain a lot of mana, but Knowledge is the Elves' second stat. So, these Druids are target number one for archers.

Added after 4 minutes
And I forgot to add that I don't see anything strange about the fact that 45 Druids don't kill either a Titan or a Dragon. The levels are too high, plus there's a penalty for shooting, plus Dragons and Titans have strong defenses, and Elves have low attack.