The Soul of the Black Coffin in Middle-Earth

This story has some elements of the game "Dark Souls", but it does not focus on game fandom, but is mainly a fantasy story that takes place in the background of Middle-earth. However, since the protagonist's golden finger 'Soul of the Black Coffin' did originally travel from the world depicted in the game, it naturally retains some memories of that world, which will be appropriately reflected in the plot. … When the fire in the world where the soul of the black coffin was was extinguished, it escaped from that world unwilling to be lonely. It has traveled through many different worlds, experienced a variety of lives, and is a wanderer in time and space. Until one day, it traveled to Middle Earth. Magic, swordsmanship, humans, dragons, castles, villages, mountains, rivers... It found that this world was very similar to its original 'fireless world', so it settled here. However, the soul of the black coffin is actually just a spirit body that lives on the black coffin. It cannot move freely, so it needs to find a host and occupy their body. In the world of Middle-earth, the Soul of the Black Coffin has hosted dozens of humans (perhaps including other races) until it met our protagonist 'Bona'. Bernard is just an ordinary soldier. He knows that the soul of the black coffin can give him power, but he is unwilling to give up his soul and thoughts. The soul of the black coffin wants to possess Bona, and Bona just wants to get its power. The story begins from there...