Reforge allows the player to randomly re-roll the perks of the weapon. Players can only reforge weapons released after House of Wolves expansion. Players can reforge at the Gunsmith npc. Each reforge costs Mote of Light, Weapon Parts and glimmer. Note that reforge will reset all the purchased perks and exp earned on a weapon.
Players can also reforge Iron Banner Weapons and Armor during Iron Banner Events in a similar but separate system.
