This quest can be started by talking to Sorcerer Vunal north of Brothers of Strife
Sorcerer Vunal at the Brothers of Strife monument says he can teach me about the past. The Brothers were apparently once mortal leaders of the citizens of Stonefalls. The pasy may hold clues about these powerful creatures.
Talk to General Balreth and Legate Sadal, collect Heartstones:
To learn the lessons of the past, I must speak to the spirits of Balreth and Sadal in the ruins of the south. I must also gather the Hearstones Vunal requested.
Talk to Sorcerer Vunal:
I've spoken with the spirits and gathered Heartstones. I should return to Sorcerer Vunal to see what comes next. He's usually studying at the base of the monument.
Find the Shrine Entrance:
Sorcerer Vunal told me to find the shrine entrance to the base of the monument. It's just a little way north up the road.
Make an Offering at the Daedric Altar:
Bunal instructed me to use the Heartstones in a ritual at the Daedric Altar.
Talk to Sorcerer Nilae:
Talk to Sorcerer Nilae.
— game journal