And if you add some azure creatures here, it will be even more intense! Maybe even some divine messengers? Azure creatures can even defeat a summoned phoenix like it's nothing! It's already quite tough, and there are many cool creatures, so there's no need to add more blue ones.

Added 2 minutes later
You're right about the efreets. Nagas are already being replaced by rakshasas, and if you create a new creature for each unit with four arms, it will look ridiculous. Heroes 5 already has enough arms! We definitely need to bring back the monsters, and also the werewolves. What about cyclops? They can be one-eyed. And if you don't make a swamp, I'll start haunting your dreams!