Combat is an integral part of the game and sometimes, you’ll encounter enemies with certain defenses that protect them from certain attacks or weak points that can be exploited.
Enemies without protection will just have a health bar. Any attack or weapon damage will be enough to kill them. These are the normal enemies you have to deal with often, for example the Kett chosen.
Armored enemies will have a yellow health bar and will take longer to take down. Fortunately, flame-based Powers like Incinerate, special ammo like Incendiary Ammo, and single-shot Weapons like shotguns and sniper rifles are good for wearing down armor. Armored enemies are immune against biotic powers like Lift, Singularity, and Throw.
Enemy shields function the same way as yours do; they won’t get damaged unless that shield layer has been depleted or taken down. Their shields regenerate as well after some time so failing to kill a shielded enemy quickly will just allow it to replenish its layer of protection. Powers like Overload, Energy Drain, as well as beam or plasma-based Weapons work quite well against shields. Disruptor Ammo can also enhance weapon damage against shields. Shielded enemies are immune against biotic powers like Lift, Singularity, and Throw.
These are usually found in bosses like the Kett Cardinal. They have special barriers that prevent any type of damage, even against anti-shield Powers like Overload. You usually have to find out the other means of disabling these shields. For Kett Cardinals for example, you have to destroy first the unshielded orbs floating around them to temporarily break their invulnerable shields and damage them normally.
Headshots deliver critical or even fatal damage on targets when hit, even instantly killing them by blowing their heads completely off. Other enemies like Remnant architects will have glowing parts of their bodies and limbs that can be damaged greatly when sniped. Sniper rifles excel at exploiting these weak points.