Canoptek Wraiths are automated Necron constructs that, like the Canoptek Spyder, oversee maintenance and repairs over all things Necrons so when the time comes to set off the alarm clock, the Crons would be all up and ready to break some spines. However, they also act like a first line security protocol robot, serving as the eyes and ears of the central operating system of any Tomb World, patrolling for intruders and swiftly dealing with them.
Its primary tool is its Phase Shifter, a Dimensional Destabilization Matrix that allows a Wraith to phase in and out of sync with the normal space-time continuum much like a C'tan Phase Blade. Though the primary purpose of this device is to allow a Canoptek Wraith to reach into and repair solid machinery, it is equally effective when used to deal with intruders who have breached the protections of a subterranean Necron stasis facility. In such a case, a Canoptek Wraith can phase its claws and tendrils inside an opponent, and resolidify them to sever arteries, nerve clusters and other vital pathways without leaving an external mark of what caused the victim's death.
Despite their similarities in function, Canoptek Wraiths are lower in class to that of the Canoptek Spyder, their relationship is thus, similiar to that of a Techpriest and Servitor of the Adeptus Mechanicus. As they are primary probe mechanoids, the Wraiths are programmed to report back to their Canoptek Spyder controllers via an interstitial interface rather than act under their own direction.
They used to look like a modified Necron Warrior like the Necron Destroyer and Flayed Ones but with the lower torso replaced with a snake-like tail and their hands turning into razor-sharp talons. The original fluff dictated that they were the Necron's chief close combat specialists (Flayed Ones notwithstanding) and it has been suggested by certain Imperial savants that in ancient days before the War in Heaven, that Wraiths were once Necrontyr murderers and psychopaths before their eternal entombment within their cold, metallic husks. Nowadays they have been given a face lift and now count as a Necron Construct, not a troop. And as you may already know they are much spookier now, despite being less skeletal.
The older design, as of 9th Edition, seems to be repurposed into Ophydian Destroyers.
These are some scary Snake mother fuckers. Did I mention they are the Grilled Cheese Sandwich of the Necron Codex. You can take them in the creepy crawlies formation. If you take 3 Snakes, 1 spider, and 3 bugs they get access to reanimation protocols among other things. They Slither over everything, and have a 3++ save. They are basically faster Lychguard with 2 wounds. Did I mention these guys are basically Necropolis Knights or Sepulchers from the Tomb Kings (rip. may your sleep be blessed). Besides that there's not much I can say.