Way of the Rift Mage

Way of the Rift Mage is a side quest in Dragon Age: Inquisition. It is one of three potential quests which a mage Inquisitor can complete in order to obtain a Specialisation.

Acquisition
This quest is not available until after From the Ashes has been completed. Go to the War Table in Skyhold, and a quest for the Inquisitor to choose a Specialisation will be available. Three potential trainers, one for each specialisation, will arrive at Skyhold to teach a mage Inquisitor a specialisation (unlike in previous games, only one can be learned). To access this quest, talk to the Rift Mage trainer (who simply addresses herself as "your trainer").

Walkthrough
Writings on rift magic: this can be obtained from either Solas or the book merchant in Val Royeaux.
 * The following materials must be required in order to finish this quest:
 * Three Venatori tomes: These can all be found in the Exalted Plains. They can be found at Ghilan'nain's Grove, Halin'sulahn, and the Desolate Bank. When a Venatori is killed in these areas, they have a chance of dropping a tome. It may take multiple visits to an area in order for them to drop one.
 * 10 ring velvet: These are a common drop from Venatori
 * Materials for a tome of rifts.

Rewards
Completing this quest will allow you to obtain the Rift Mage Specialisation.

Other

 * All three specialisation quests can be done at once, however, only one can be completed.