The Lord of the rings characters are copyrighted. The idea of a fantasy story set in a fantasy world isn't.
Copyright can only be assigned to something that is made. Frodo the hobbit is a copyrighted character but Hobbits is a copyrighted name, halflings is an idea.
Legolas the elf is copyrighted but elf is a public domain name for a race.
3 hours ago, ramdy said:I could call it "The Ring of the Lords" but the story to happen in the middle earth,
The Ring is a copyrighted name for a key item of a story set in middle earth; so your idea is possibly infringing on copyright.
"The Crown of the Lords" a story set in middle earth is not a infringement of copyright, because none of those are owned IP yet. Middle earth is public domain; although Tolkien's Middle Earth, characters and names is copyrighted.
Note: Tolkien's Middle Earth, by adding the name infront it is made clear that it isn't the public domain name.
The contend made for the story and written down, can be copyrighted. The same way RPG characters can be copyrighted. A Battle system can also be copyrighted, once it exists; but it only protects people from cloning it directly.
People can still make battle systems similar to it, or improve on the idea. Assassin's Creed VS Shadow of Mordor is a good example. By not using any Assassin's Creed copyrighted content, Shadow of Mordor made a similar game from scratch.