Lost Forges is a new activity type introduced in the Black Armory downloadable contact pack for Destiny 2: Forsaken. This activity is a three player Horde activity that also supports matchmaking, unlike Escalation Protocol.
This activity consists of three waves of enemies, two of which have special blue enemies that drop batteries for the forge.
In all forges in wave 2, two drones (similar to the saboteur drones) spawn in different locations. Taking them out provides the players with the perk "Maximum Temper" that provide an extra rewards chest at the end, and is also vital to the mystery box quest.