Den Of Heroes Artefact
The main reason behind that was the inability for them to gather up and store death energy on their own. Just like my soulers, if they weren't present in a place filled with killing and death, they wouldn't survive.
So only the big powers in the universe kept large numbers of such mighty races. A mighty race cursed with his powers, ending up being warriors, serving others for just keeping themselves alive.
And this artefact here was one of the ways big forces used to keep them alive.
Interesting! That sovereign offered me such treasure and didn't offer me a way to exchange necromancers.
Was he thinking so high of his necromancers or too low to not include them in our deal?
As I read more about this artefact, I got more impressed with it. It wasn't just a tool to create a separate place in any world, but it worked as a way to filter the death energy into real things anyone could use.