Way of the Assassin

Way of the Assassin is a side quest in Dragon Age: Inquisition. It is one of three potential quests which a rogue Inquisitor can complete to obtain a specialization.

Craft a proper knife, study the methods required to wield it, and Heir will reveal the secrets of the Assassin specialization. Kill guild leaders for their tokens at the East Side Hills, the Flats, and the Black Fens in Crestwood. Readings can be found among the belongings of followers who share this discipline. Or, if unavailable, among the wares of the book merchant in Val Royeaux.

While a rogue can only truly specialize in one style, studying others can still be of considerable benefit.

Acquisition
This quest is not available until you complete From the Ashes and reach Skyhold. The War table operation, Specializations for the Inquisitor will appear when you leave Skyhold for the first time and return.

Three potential trainers, one for each specialization, will arrive at Skyhold to teach a rogue Inquisitor a specialization (unlike in previous games, only one can be learned). To access this quest, talk to the Assassin trainer, Heir.

Walkthrough
The following materials are required to craft The Murder Knife: Northwest of New Crestwood, at a dock on the lake. West of New Crestwood, near the Fisherman's Shack. South of the dam, west of the dragon encounter at a quarry. It is also obtainable by killing assassins in Valammar.
 * Writings on Assassin methods. This can be obtained from the area next to Cole in Skyhold or the book merchant in Val Royeaux.
 * 3 Assassin Guild Leader Tokens. These can be looted from bandit leaders throughout Crestwood:
 * 20 Deathroot. These can be found throughout the Western Approach. They are also available for purchase at the village in Crestwood.

Craft the knife at a requisition table and bring it to Heir to complete the quest.

Rewards
Completing this quest will allow you to obtain the Assassin specialization.