Ring of Phynaster Location - Morrowind
Location: Senim Ancestral Tomb
Requirements: Able to open a lock level of 50
Video: How to get the Ring of Phynaster
The Ring of Phynaster is found inside of the Senim Ancestral Tomb which is a very short walk southeast from Dagon Fel. Inside this tomb you'll find a bunch of undead enemies and a random assortment of half way decent loot. Many scrolls and other items can be found scattered throughout the entire tomb - so be thorough when clearing the dungeon!
You'll find the Ring of Phynaster in the back of the dungeon on the skeleton corpse of Pop Je. To reach the body you'll need to have a method for bypassing a lock level of 50. This body is another Easter Egg to someone who passed away while the game was being developed. Check out the UESP wiki entry for more information. Surrounding the corpse will be an entire set of Bonemold armor if you're interested as well.