Cerberus Nightmare Armor Effects +20% Ammo Capacity+20% Headshot Damage+20% Weapon Damage+10% Shield Regen Speed+10% Shields Starting Health Starting Shields Availability The Cerberus Nightmare Armor is a set of armor in Mass Effect 3, available by completing an Armax Arsenal Arena challenge in Mass Effect 3: Citadel. It increases shields, weapon damage, and ammo capacity.