|Bosses||Valus Dulurc (Colossus)|
Fast travel to the Glacial Drift and turn around. You should immediately see the lost sector sign on the nearby cave wall. Head to it, eliminating the occasional Incendior on your path. Drop deeper and deeper into the cavern till you reach Ma'adim Subterrane. Immediately, you will be attacked by Legionaries, Centurions, Psions, and War Beasts. Climb up the cave complex, killing off Gladiators and Phalanxs in the process. Soon, you will reach the final room with Valus Dulurc. It's best to use Super or hit him with a couple of rockets from a safe distance. When the battle is over, make sure to open the loot chest located right next to him
Hidden loot box can be found in the bush on the right side just before the entrance to the lost sector.