Diagram: Grandmaster legendary forgotten Wolven trousers is a crafting diagram in The Witcher 3: Wild Hunt introduced with the next-gen update, Patch 4.0. It is needed to craft Grandmaster legendary forgotten Wolven trousers in New Game +.
This one, along with all the other mastercrafted and grandmaster diagrams for the set, is given after completing Scavenger Hunt: Forgotten Wolf School Gear Diagrams.