Triune Amulet

The Triune Amulet is a rare necklace.

Source
This item drops from High Inquisitor Whitemane in the Cathedral Wing of The Scarlet Monastery.

Trivia
It should be noted that the Triune was also a cult religion in the Diablo trilogy The Sin War, by Richard A. Knaak. The followers of the Temple of Triune falsly worshipped the Three Prime Evils; Diablo, Mephisto and Baal, the Lords of Terror, Chaos and Destruction. This may be a reference to it.