Creating your own hero.

Could you please tell me if it's possible to create custom heroes with new abilities, rather than just changing names and choosing from existing ones? For example, creating a hero with an ability that grants +1 attack and defense for every two (or three) levels, specifically for Monks, etc. Or +1 to maximum damage for Undead. In general, uploading a picture and writing a biography isn't a problem, but I'd like to be able to create something unique. Can anyone help? I'm sure there are people who know much more about the editor than I do.