Acquire all seven legendary sorceries and incantations:
Flame of the Fell God: Dropped by Adan, Thief of Fire upon defeat
Greyoll's Roar: Can be purchased at the Cathedral of Dragon Communion for three Dragon Heart after defeating Greyoll
Elden Stars: Can be found near the Great Waterfall Crest Site of Grace
Ranni's Dark Moon: Found in a chest at the top of the tower at Chelona's Rise
Comet Azur: Acquired from Primeval Sorcerer Azur sitting near the cliffs in the northeast of Hermit Village in Mt. Gelmir