- "Trade speed for power—shift biomass to your forearms to allow deadly area-effect attacks, crush guarding enemies, and shatter armored vehicles. Hammerfist delivers the pain."
James Heller also acquired his Hammerfists after consuming the DNA of a variant of Juggernaut which was able to create groundspikes. Heller was capable of devastator attacks with Hammerfists effects and creating groundspikes similar to Mercer's Claws.
Hammerfist Elbow SlamEdit
- "Jump up, drop down. Deadly against armor. Add extra height to increase your damage and area of effect. With the right conditions, you can crack an enemy Tank with a single blow."
Hammerfist Elbow Slam is the second upgrade of Hammerfist. It is essentially the normal elbow slam maneuver with the upside of increased damage and area of effect, as well as not requiring the running up of a wall to execute. Like the Hammerfist Smackdown, this move can help in destroying armored vehicles and Hunters. In order to use this power, the Prototypes will have to gain some altitude, before dropping down on an enemy with a deadly force. The higher the altitude and attack charge, the more damaging the attack.
- "Sprint into a self-throw and put all your weight into a single, concentrated attack. The Hammertoss is dangerous when you miss—and deadly when you hit."
Hammertoss is the final upgrade for the Hammerfist. This upgrade helps to deal with airborne enemies, like the Gunships and UAVs to a limited extent. It is also a handy way to toss Mercer over obstacles and clear out his landing area of any minor enemies.
- "Blast enemies out of your path with this powerful combo. It is slow, but powerful- especially effective against enemy armor. Be wary of using against faster opponents."
Hammerfist Smackdown, the first upgrade for the Hammerfists, is an slow but highly damaging slam attack. Capable of destroying early armored vehicles with a single direct hit, but at the cost of attack speed. While charging the power, Mercer is susceptible to being interrupted by attacks. Otherwise, a fully charged attack has the effect of delivering two shocks upon anything within range.
|Hammerfist Power||Behind the Glass||48,000|
|Hammerfist Smackdown||Behind the Glass||48,000|
|Hammerfist Elbow Slam||Biological Imperative||675,000|
|Hammertoss||Making the Future||900,000|
The Hammerfists are quite capable in anti-vehicle combat, as repeated strikes will lift APCs and tanks off the ground, preventing them from retreating. They are also quite useful against Hunters,especially Leader Hunters who will be stunned by the heavy strikes. Even Super Soldiers will quickly enter their blocking stance after sustaining a couple of shockwaves, which Alex can exploit to a grappling advantage.
In close proximity, it can be used to clear large groups of human enemies quickly. If Alex charges up his punch, he can knock one enemy horizontally into another, instantaneously killing both enemies. He can also use a four strike combo that shatters the street and creates a shockwave dealing heavy damage to everything nearby. 
The Hammerfists lack attack speed and is slower than any of his other abilities. Unless Alex strikes point-blank, enemies are liable to move out of range or retaliate before he can get a hit in. Armor, especially when moving, can be difficult to hit unless Alex gets in their path.
Though powerful, the Hammerfists are quickly eclipsed by Alex's other offensive powers in terms of damage over time. Though the Claws are weaker in most respects, Musclemass, the Blade, and even the Whipfist do more damage over longer periods thanks to their greater attack speed. Musclemass, used in conjunction with Alex's various combat moves, will do far more damage over time than the Hammerfists, with the added versatility of enhancing his throwing power.
The Blade will do more damage over time to living enemies than the Hammerfists will, and the Air Blade attack will reliably kill tanks from any height, whereas the Elbow Drop of the Hammerfists needs to be done from a significant height to accomplish the same.
Like many other powers, the amount of moves available with the Hammerfists is reduced. Heller is able to use the Hammerfist Elbow slam, and a small combo chain.
Heller's ability to create groundspikes stem from the Hammerfists instead of Claws. Holding the attack button will push Heller's hands into the ground, launching up spikes around him.
There are three ways to do this, when in the air, holding the attack button will propel Heller downwards, fists first, and spikes will plunge upwards around him, in a circle, similar to the Groundspike Graveyard Devastator in Prototype, but smaller.
Second, is at the end of the combo (Tapping the button), Heller will launch spikes out of the ground, around him in a circle, just like the first method. Third, is to be on the ground, and hold the button. This results in a forward shockwave of spikes, traveling in a single direction.
Upgrades in Prototype 2Edit
- Level 1 - Hammerfists acquired
- Level 2 - Hammerfists damage radius increased.
- Level 3 - Range and size of Ground Spikes increased.
- Level 4 - 25% boost to Hammerfists attacks.
- When standing still, Alex slumps over and hangs his fists down, obviously hinting at how heavy they are.
- This is the only power that has an idle animation, in Prototype. If Alex remains idle for a few seconds, he will beat his fists together.
- Alex will still perform the Hammertoss move during the final boss fight in Prototype 2.
- This is the only power in Prototype 2 which has a 4-hit combo. Other powers have a 5-hit combo.
- Performing a helicopter finisher with the Hammerfists uses the same animation as an unarmed finisher.
- As a physics goof, one wonders where the mass for the especially heavy-hitting hammerfists come from, seeing as they do not visibly affect Heller's mass ie. when he glides, stands on top of fragile objects, etc.