Hunding's Rage is part of the base game. The crafting stations are located in Reaper's March (Broken Arch), Bangkorai (Wether's Cleft) and The Rift (Trollslayer Gully). 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.