Amulet of Heartfire Location - Morrowind
Requirements: Able to open a lock level of 20
Video: How to get Keening & Amulet of Heartfire
Amulet of Heartfire is a powerful enchanted amulet that can only be acquired by defeating Dagoth Odros and looting it from his corpse. You will be tasked with defeating Dagoth Odros towards the end of the main story of Morrowind, but like with almost all things in this game you can technically find and kill Dagoth Odros at any time.
Dagoth Odros is found behind the walls of the Ghost Fence in a dungeon by the name of Odrosal. While Levitate isn't required to reach this dungeon it is highly recommended since the landscape of this area is a total nightmare to navigate. Levitate will allow you to go straight to your destination instead of having to follow the indirect path there.
You'll find Dagoth Odros inside the Odrosal, Dwemer Training Academy on the 2nd floor. He's both easy to find and easy to defeat. In the Odrosal Tower section of this dungeon you'll find the Keening Artifact (Weapon) which is one of the required items for completing the game.