[Endoperez]

You can't make a nation's dominions spawn free critters, but you can make a creature spawn units in various ways. I don't remember how it worked, exactly, but I think there are commands for:

- summoning units based on your dominion strength in the province, similar to Vampire Queen/vampires, Ghost King/ghosts etc

- automatically summoning few units of a spesific type every turn

- automatically summoning few units of a spesific type at the start of battle, at least if you use custom spells. It probably isn't possible to make cross-breeding a battle-spell.

- spending a turn to summon few creatures of a spesific type

Most of these can be combined with each other, but IIRC you can have only one of the three types of domsummon on the same unit.

These can be combined to summon 2-3 different types of creatures.