- "Transform your hands into deadly edged weapons; slice and dice for up-close crowd control."
The Claws are an offensive ability developed by Alex Mercer and James Heller. Mercer was able to unlock this ability after consuming a Hunter. Similarly, Heller gained his Claws by consuming a Brawler. 
When activated, the biomass of the arms shifts into three-fingered, one-thumbed talon-like appendages that can used to shred flesh and bone, allowing dismemberment of human-sized enemies with ease, however it is less effective against armor and larger Blacklight creatures.
- "Slice. Cleave. Slash. Gore on the move."
Dashing slice is a movement upgrade to the Claws. It is the most powerful slashing-type of attack available from the Claws. Since it is performed while sprinting, charging the attack automatically slides the Prototypes towards the target before delivering the slash. This helps in rapidly closing the distance to the target and can automatically stop to perform a Groundspike attack easier.
- "Shift your mass into a deadly spike that erupts beneath your enemies. Combine with targeting for pinpoint spike precision."
Groundspike is an upgrade and an extension to the Claws. It is highly effective for short or longer-ranged area attack. The biomass from the Claws are channeled into the ground to erupt and impale a targeted enemy or a tight group of enemies. This power can be upgraded to cause maximum damage and area effect. This ability is useful for destroying infected water towers with one strike.
|Claw Power||Behind the Glass||none|
|Groundspike||Behind the Glass||50,000|
|A New Order||80,000|
|Dashing Slice||A New Order||65,000|
The Claws are best put to use as an anti-personnel weapon; their speed allows to shred through large groups of infected and humans in seconds. When upgraded with the Groundspike ability, damage can be caused to distant enemies by clawing the ground and causing massive spikes of Biomass to erupt beneath the target, impaling everything within its proximity. This ability is particularly useful to deal with armored vehicles, and even some larger infected enemies.
Although the Claws have their advantages, basic attacks are ineffective against armor, D-Code soldiers, and larger infected. In close combat, the damage dealt against them is very low when compared to the Groundspike attack. Unless attacking a lone target, the Groundspike ability forces Alex Mercer to remain stationary for the duration of the attack. This results in a moment of vulnerability allowing enemies to attack him.
Heller's Claws are mutated beyond Mercer's in that they are usable for aerial combat. Heller is capable of attacking an airborne vehicle, causing reasonable damage. His Claw Pounce maneuver improves on Mercer's Dashing Slice by being able to attack at any degree of elevation while grounded or airborne. Heller also can further mutate his Claws, increasing the rate of damage dealt.
Claw Pounce is a charged attack, in which Heller will start by extending his Claws like he is about to pounce like a real Jungle Cat, next he will enhance his leap with his biological cells similar to his glide power and slash at the target.
Level 1 - Claws acquired.
Level 2 - Claws range increased 25%.
Level 3 - Claws Pounce range increased.
Level 4 - 25% increase in Claws damage.
- Claws in Prototype only use one claw in each paw to strike. Charging a strike allows you to see only the claw in question extend in length before striking. This would help to explain the clean cuts on humans and basic infected.
- The edges of Heller's Stage 1 Claws resemble a military combat knife, and the stage 3 edges are more spiked fused with curves and replacing the military combat knives.
- Heller can perform a Claw Pounce attack to bridge the gap with faraway enemies. Also, the Claw Pounce can be done with the airborne grab in either order, once each, between every feet-contact with the ground/wall. This allows Heller to increase his horizontal travelling distances even more during his last gliding descent.
- During the final battle between Heller and Mercer, Mercer's Claws are extremely small, almost the size of his hand.
- In [PROTOTYPE], when Alex walks, his claws detract to a size similar to what is seen in [PROTOTYPE2].
- In Prototype 2, Mercer stays true to his original power configuration—switching to his Claws to deliver Hammerfist-styled groundspike waves.