One Ring

The One Ring is the ultimate weapon of the Dark Lord Sauron. It greatly increases the users physical and magical strength, and in the case of Sauron, keeps him alive. No matter how badly Sauron is beaten, the ring will ensure that his spirit endures.

The ring was forged by Celebrimbor in the blazing fires of Orodruin. As that was where it was made, it is also the only place it can be destroyed.