DISCUSSIONS on “Rules for online games in HoMM3 and formulas for calculating player rating.”

I think if you leave such a hero as a "sacrificial lamb" without having them participate in battles throughout the game, you might not need to resurrect them. For example, Valya, level 10, goes out to explore, while the purchased Taz stays in the stronghold.
Similar situations have already occurred, and they resolved it amongst themselves, so to speak.