Heroes 5.5 WarGame Edition - Tactical Edition.

Undead: Deydra (Banshee): The hero's "Banshee's Wail" ability is enhanced: the penalty increases from -3 to -5. (no initiative penalty) Markel (Death Lord): 1 lich joins (and continues to join) the hero's army for every 4 levels of the hero. (cost of 1 lich = 1500) Ornella (Cursed Queen): The "Curse" spell is enhanced. In addition to its usual effect, it reduces the target's defense by 1 for every 4 levels of the hero, starting from the first. Vlad (Resurrector): The "Raise Dead" spell is enhanced; when used, the hero's magic skill is considered to be 1 higher for every 2 levels of the hero, starting from the first. Orcs: Keegan (Goblin King): The "Goblin Aid" ability is enhanced: from +4 goblins per hero level to +8. (cost of 1 goblin = 100) Garuna (Blood Drinker): Each enemy unit (including summoned troops) killed increases the attack of all creatures in the hero's army by +1 for every 7 levels of the hero, starting from the first. Kujin (High Shaman): 1 shaman joins (and continues to join) the hero's army for every level of the hero. (cost of 1 shaman = 350) Shak (Wyvern Tamer): Wyverns in the hero's army receive +3 to health for every level of the hero. Argat (Wolf Lord): The "Pack Leader" ability is enhanced: from +4 wolves per hero level to +6. (cost of 1 wolf = 200)

Added 32 minutes ago

regarding elemental immunities - they should be possessed by elementals, dragons, and units whose nature is related to a particular element (for example, phoenixes are related to the element of fire)

The problem is that dragons are not made of stone. At best, earth immunity can be given to emerald dragons. Otherwise, the question will arise of giving all dark dragons immunity to Darkness (which, of course, does not exist in the game)