Slicer, called Kamakiller (カマキラー) in the Japanese manual, is a badnik from the 16-bit version of Sonic the Hedgehog 2 found in Metropolis Zone. It is a praying mantis-like creature with two claws that it launches at you. The claws will home in on you for a couple of seconds, but when you destroy the creature itself the claws will stop following you and drop. They are usually positioned in awkward locations so that it is hard to get past them.
The enemy reappeared in Gigantic Angel Zone from Sonic Pocket Adventure, they appear much like the Metropolis Zone at this stage.
The Slicers re-appears in Sonic 4s in Mad Gear Zone. But with a much more updated design, but it has the same function of previous games, but unlike the classics, after he shoot his claws on the player, it starts to glow and soon after self-destructs.
Also appears in Sonic Lost World at various stages individually, they have the same pattern of attack that of previous games, but their claws will respawn after play. In the version of Wii U they are found in Zone 2 of Silent Forest and in Zone 3 of Lava Mountain. While the version of the 3DS they are found in Zone 2 of Silent Forest and in Zones 1 and 3 of Sky Road.