Then, upon reaching the heavens, the hero should be given a certain number of "guardians" (creature-spirits) based on his race. And each hero will use them according to his abilities. If the hero is killed in the heavens, he will die permanently, but if he kills several heroes himself, he will return to the normal level.
Справочник по НоММ-4 http://handbookhmm.ru/pamyatka-dlya-heroes-iv.html
Памятка по НоММ-3 http://handbookhmm.ru/pamyatka-dlya-homm-iii.html
и HotA http://handbookhmm.ru/vyishla-obnovlennaya-pamyatka-dlya-homm-iii-hota.html