A Canoptek Leech is a Necron robotic construct that is primarily dedicated to repairing the living metal, Necrodermis, that comprises all Necron android bodies, artifacts and vehicles. However, Canoptek Leeches are also integral to the function of the arcane prisons and war engines known as Tesseract Vaults, which contain and harness the form of a Transcendent C'tan. They are tasked with continuously repairing the walls of the vault which are routinely destroyed by the energies released by the captive C'tan Shard.
Transcendent C'tan are nothing less than the amalgamation of dozens or even hundreds of lesser C'tan Shards, and are of such size and indomitable will that they are too powerful to be contained within the extradimensional intricacies of a Tesseract Labyrinth. As such, a Tesseract Vault serves as both a prison and a conduit for their power instead. Bound within the vault’s heart, the star vampire will fight against its bonds; and such is the elemental might of the C'tan that the walls of the Tesseract Vault are perpetually being destroyed by the insane energies the Star God releases. It is only the unceasing ministrations of the ever-vigilant Canoptek Leech guardian constructs arrayed and docked around the exterior hull of the Tesseract Vault that keep the C'tan in check; these, and the robotic construct known as a Canoptek Sentinel that encloses the C'tan itself in a force shield generated using a portion of the C'tan's own power that is held together by its eight writhing, mechanical tentacles. However, there are only so many Canoptek Scarabs and Canoptek Leeches holding the Tesseract Vault together, and as the Transcendent C'tan bends reality and tears metal off the vault in its bids for freedom, the Canoptek automatons rebuild its prison using the debris in a cyclical process of destruction and reconstruction.
- Apocalypse (6th Edition), pp. 170, 173
- White Dwarf 404 (July 2013) (AUS), pp. 10-13, 144-145