Nibrosu tried to implement +1 for every 5 levels.
Regarding the new specializations: in my map, I implemented an additional specialization for Nibrosu in the form of a daily bonus to certain parameters (i.e., for one day, he has something temporarily increased, such as attack, defense, or even experience; this is determined randomly. The next day, this bonus is removed and replaced with something else). Something like that.
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Oh, so you gave Talannar machines? Well, now he's a completely different hero ;)