The Reaper grabs the victim with its upper talons and uses it's lower ones to thrust and stab the body of the victim over and over until the player eventually dies. This is an instant death attack, so watch your distance.
Avoiding close quarter encounters is recommended. The player should engage the creature from a distance with a sniper rifle. If the player has a good aim, they can use either machine guns or handguns and aim for their weak spot located on their back.
Should the player insist on engaging the creature in close range, use a shotgun and wait for the creature to ready itself to attack. It will expose its abdominal sac by doing so. Be quick though, as being careless can result in being killed.
Acid Rounds and Electric Rounds work well against the creature. One shot from any of the rounds mentioned should expose their weak spot.
If the player wants to get past the creature and find a breathing space, use either, Explosive Rounds or Hand Grenades, to make them curl up and roll. This should give the player an opportunity to get past the creature and find an opening to attack.
A Rocket Launcher should kill the creature instantly, provided that the player aims for the Reaper. If the player misses the shot but the creature is hit by the explosion radius, it will curl up and roll.
Shooting off their appendages will cripple a Reaper; the removal of an arm will stop it from using its Puncture grab. However, Reapers are capable of regenerating limbs extremely quickly, taking only a few seconds to repair its head, arms, or legs. The only two ways to kill a Reaper are to shoot the glowing abdominal sac when the armor plating shifts off to vent gas, or by hitting the Reaper with explosives powerful enough to obliterate its body completely (such as a direct hit from a rocket). The Reaper also has two glowing sacs on its back, which when destroyed stuns the Reaper and forces it to prominently reveal its abdominal weak point.
The Reaper attacks primarily by using its upper claws to grab a target, and using its middle scything talons to repeatedly puncture and shred the victim's abdomen, an attack from which the victim cannot be saved. When one or more of its claws are destroyed, the Reaper can still counterattack by slashing with its remaining appendages. The Reaper can quickly close distance on enemies by crawling on its six appendages; however, while doing so it cannot attack, revealing the two glowing sacs on its back.
Reapers vent noxious gases from their dorsal and abdominal sacs while exposing their weak points, creating a blur effect that acts as a simple yet effective form of cloak, making difficult to aim at their vitals. Fire is extremely ineffective against a Reaper (incendiary grenades cannot damage a Reaper's weak points, remove its limbs, or slow it down in any way). However, it is possible to kill a Reaper by exposing it to constant, intense heat, such as leading it into an incinerator as seen in Chapter 5-2.
When hit by a weak explosion, Reapers will instantly go into a long rolling animation and cannot attack while doing it avoiding damage.