30 minutes (or endless amount of time if you take the power core out to pause the timer) of killing demons. Gain Argent Energy from killing demons and use that energy to buy weapons, equipment, or increase damage, ammo capacity, health, or armor. If playing coop, it becomes a competition to see who can have the most Argent Energy at the end of the game. If you die, you respawn you lose your equipment, but not your energy. Argent Caches spawn in random locations around the four arenas every two minutes; picking one of these up gives 500 Argent Energy.