Kingdoms are supposed to have Life mana, Empires Death mana.
If you place an outpost, and steal a death shard while it is being constucted as a Kingdom, the Kingdom ends up with a death shard. Unsure if you can destroy and rebuild, or if it works in reverse.
One idea/suggestion: rename Life Shards and Death Shards to Soul Shards or Void Shards or something else, the distinction is flavor, but doesn't add anything at all to the game, and is a cause of a few bugs/glitches. Have life and death spells both work with the new shards.