However, procuring this mysterious core is not an easy task, as it can only be found within the perilous Mistlands biome.

Source: https://screenrant.com/how-to-get-use-black-cores-valheim/

The latest update to has added an entirely new biome to explore and conquer: the Mistlands.

Source: https://gamerant.com/valheim-mistlands-survival-guide/

To get Black Cores for crafting high-end workstations in Valheim, players must venture into the Mistlands in search of the biome's dangerous Dungeons.

Source: https://screenrant.com/how-to-get-use-black-cores-valheim/