A Necron air defense construct and nearly indestructible war machine, an Obelisk is similar in design to a Monolith but vastly different in function and purpose. The function of these cyclopean mobile fortresses is to watch and await the inevitable day when a lesser race will risk their army against a Necron Tomb World. They are almost undetectable in the quiescent state and can be sustained in that state for thousands - if not millions - of standard years on the smallest current used to power a powerful energy shield.
An Obelisk only comes into full function when it spots enemy aircraft in the skies over the burial world of its Necron masters and the sky darkens with the shadows of dogfighting fighters. When he does so, his energy field is deactivated, but by manipulating a tiny gravitational singularity within it, an obelisk beneath the tomb world's crust is able to rise into the air, approaching quickly but silently.
Should an enemy aircraft get too close, the Obelisk can unleash a Gravity Pulse, an expanding sphere of seismic gravimetric force that blasts enemy aircraft out of the sky, plunging the intruder to a fiery death. As such, when an Obelisk is activated, it rises to complete dominance over the war-torn surface of its homeworld. It will obliterate any enemy in the airspace around it, even obliterating ground-based targets with its sinister Tesla Spheres.
Transcendent C'tan are the most dangerous of the C'tan Shards. Each is a collection of anywhere from a dozen to a hundred smaller C'tan shards, and their power far exceeds the sum of their parts.
The few chained to the service of the Necrons are bound not by Tesseract labyrinths but by chains of energy designed eons ago by the legendary Necron constructor Svarokh.
Such devices are unstable, making deploying a Transcendent C'tan without the device known as the Tesseract Vault a risk only undertaken in times of dire need. For this reason, when contained within a Tesseract Vault, a Transcendent C'tan is also contained within a special energy shield created by a robotic Necron construct called the Canoptek Sentinel.
Canoptek Sentinels are used to control the raw elemental energies of a transcendent C'tan. The Sentinel draws on the Transcendent C'tan's own power to create a force shield strong enough to bind the C'tan to the mechanisms of the Tesseract Vault.
At the same time, constructs known as Canoptek Leeches are strung and docked around the vault, and an army of Canoptek Scarabs move to constantly repair the damage done to the arcane prison.
However, there are only so many scarabs and Canoptek leeches holding the Tesseract vault together, and while the transcendent C'tan bends reality and rips metal from the vault, the Canoptek automatons cyclically rebuild their prison by using the Debris use process of destruction and rebuilding.