Willow's Path is part of the base game. The crafting stations are located in Reaper's March (Greenspeaker's Grove), Bangkorai (Viridian Hideaway) and The Rift (Smokefrost Vigil). You can craft any armor, weapon or jewelry of this set in any motif style you know, as long as you have 6 traits researched (per item). You can trade crafted pieces to other players. Each set item becomes bound on equip.