The Defensive Powers are abilities which provide protection against enemy fire and attacks. Although only two abilities have been evolved, both are advantageous and highly useful.These powers cannot be upgraded further.
- Main article: Armor
The Armor consists black plates of hardened biomass; formed all around the body. While in this form, Alex Mercer was equivalent to a humanoid tank. This ability increases damage resistance overall, at the cost of movement and the ability to parkour.
- Main article: Shield
The Shield power is incredibly useful defense ability. It soaks up damage automatically until it shatters and regenerates automatically. However it's regen rate depends upon the health upgrades available. The Shield can be left activated permanently but will disable the ability to perform parkour. 
Alex Mercer was capable of channeling his biomass only to his left arm, however James Heller can shift his biomass to both of his arms creating dual shields.
James Heller has the unique ability of being able to deflect rockets and other projectiles back at the enemy that fired it using dual shields. They are also indestructible. He can perform this move either in midair or on the ground. Unlike Mercer however, Heller can't move while his shield is activated. Despite the large gap between Heller's two shields, he is able to completely block attacks from all directions. The Hydra is one of the few enemies that can damage Heller while his shields are up.