The Amber Friend is a possibly-guaranteed artifact ring. The ring is found on an Altar inside of the Vault, and is the subject of a number of new interactions with the townsfolk. The item identifier will tell you a legend about the ring, and Lord Gazkhar will attempt to buy it from you with gold.
The ring itself is exceptionally powerful. Besides being very light (no movement speed reduction), the ring slows nearby enemies, lowers the dodge/fire resistance/cold resistance of nearby enemies, has fantastic resistances (confusion, evil, and cold), and finally has increased to both XP gained (25%) and attack block (-5 incoming damage).