Fortified Brass is a craftable set. The 5-piece bonus adds 5170 Physical Resistance and 5170 Spell Resistance.
Fortified Brass is part of the Clockwork City DLC. The crafting station is located in Clockwork City (Brass Fortress). You can craft any armor, weapon or jewelry of this set in any motif style you know, as long as you have 4 traits researched (per item). You can trade crafted pieces to other players. Each set item becomes bound on equip.