Slicer (カマキラー,Kamakiller?) is a mantis-type Badnik, that is created by Doctor Robotnik. Slicer makes its first appearance at Metropolis Zone in Sonic the Hedgehog 2. Slicers are temporary dangerous guards along with other Badniks of Metropolis Zone with their sharp and even irritating claws.
Sonic the Hedgehog 2
Slicers make their debut in Sonic the Hedgehog 2 as they exist in the Metropolis Zone, which has three acts unlike others that had two. Slicers can usually be found at the edges of gorges where the player often bounce out or they can block a narrow point of the route.
Slicers can also be found hanging on ceilings. As it has been mentioned before, Slicers are really vulnerable after it throws its claws to the player. Without them, it can be defeated with any attack possible and even if Slicers have its claws, it is possible to attack them behind. Slicers are often found near the other two Badniks of the Metropolis Zone: Asterons and Shellcrackers.
Slicers makes their return in the Mad Gear Zone in Sonic the Hedgehog 4. Despite having an updated look, they pretty much act same like in past games and because of Homing Attack, they are now easier to defeat. Also, if the player lets Slicer live after throwing its claws away, it starts flashing and self-destructs itself.
Sonic 4 Website info
Slicer - how could we ever forget you? The one Badnik everyone loves to hate. Slicer can fire off its arms at our blue hero, making it a formidable foe that will require a lot of practice to defeat unscathed. Timing is key, so don’t hesitate for a second if one of these robots spots you!
Sonic Lost World
Slicers make an appearance in Sonic Lost World, where they are seen individually through the game and has the same attack pattern from previous games. During the game, it turns out that Badniks, including Slicers, got hijacked by the Deadly Six. In Wii U version of the game, Slicers are first seen at Silent Forest Zone 2 and a single, craftily placed one is seen lurking at the mid-point of Lava Mountain Zone 3.
Slicers in Nintendo 3DS version of the game are apparently seen on groups rather than being placed individually. Their attack pattern is identical from Wii U version. They are featured on Silent Forest Zone 2 and Sky Road Zone 3.
Slicer as a Badnik is based on a mantis. Slicer's head is flat and has yellow eyes with small pupils. Like Moto Bug and Buzz Bomber, Slicer has two metallic teeth. Each of its hand has razor-sharp claws, which are its primary weapons. Slicers have thin legs, and each foot's heel has small wheels. He moves slowly with them. These small wheels later don't exist in the updated look.
When Slicer notices the player, it throws its claws in a boomerang-like fashion. This attack is surprisingly hard to avoid, although the Slicer is very vulnerable without its claws. In Sonic the Hedgehog 4, after throwing their claws, they self-destruct if left alone for a while. Slicers are quite infamous for their somewhat unavoidable placements.
Slicers return years later at the Genesis arc in # 229, as they guard the inside route of Metropolis Zone, when Sonic is heading to Doctor Eggman. In this story arc they got an updated look, taken from Sonic the Hedgehog 4.
Slicers reappear in one panel of Issue 255. In this issue, these Badniks are part of the forces dispatched to prevent Sonic, Tails, and Bunnie's escape from Metropolis Zone.
Because of their single attack and unavoidable placements, Slicers are usually considered as one of the most difficult enemies in Sonic the Hedgehog 2.
Like Shellcracker, Slicers for odd reason disappear from places where they should be in Metropolis Zone. This is especially noticeable at the last High-speed elevator section in act 3 of Metropolis Zone, where Slicer is supposed to appear in front of the High-speed elevator, but sometimes this Slicer disappears from that location when the player visits on another time. Presumably, it enters the elevator and is teleported somewhere else if the player waits long enough to discover it.