Temple of the Triune
From Diablo Wiki
The Temple of the Triune is the opposing relious sect to the Cathedral of Light and is ruled by The Primus and is composed of three deities: Bala, Dialon, and Mefis. Bala stood for Creation, represented by a leaf. Dialon was the spirit of Determination, symbolized by a stubborn ram. The spirit of Mefis symbolized Love, and acolytes of Mefis wore a red circle on their breastplate to symbolize a heart. The Temple had Peace Warders, who were the warriors of the Temple.
The Triune have temples established in various locations and all have a underground area where demonic rituals are practiced. There are also vicious beasts who have no eyes and are merciless called Morlu.