Seriously GW, don't you think that you have already assraped the C'Tan enough already?
The Tesseract Vault is a Necron machine which contains the essence and power of a Trascendant C'Tan. But at the same time let the C'Tan uses his/hers/its massive powers exactly the same as it was on its own.
In defense of the poor power-stripped C'Tan I'll say that he/she doesn't like that (and who would?) and he uses every bit of power left within him to unshackle him/her/itself by destroying the Vault bit by bit in the process... if weren't for the legions of Canoptek Spiders and Scarabs who repair it continually, rendering his/her/its efforts irrelevant and useless.
Basically, there's two versions of the Tesseract Vault you can choose from. You can have the AV 14 floating recliner for your C'tan shard, or you can be ballsy and split the two. With the latter option, the Tesseract vault transforms into the Obelisk. This gives you a bad ass monolith that auto hits flyers.
7th Well, now both of these things are mentioned in the codex.
The Vault has now gotten a "boost..." Keeps the Apocalypse aspect of lots of Hull points to take hits (AV 14 all round, as Necrons like it). This thing is just an upgraded C'tan, now that may not sound that impressive at first glance, but when you look at the upgrades it's rather fitting.
This thing is meant to be sent in and explode in the face of the enemy, as a big shooty floating distraction from the rest of your army. It even got a specific rule that says that it will explode. So let it do it.
Still pretty big hovering thing that will (have a chance of) deal out some damage no matter what you shoot at.
Should be noted that since escalation is still sold the old rules are still legal.
- Apocalypse - This is the game mode where you can play this... thing.
|Forces of the Necrons|
|Command:||Cryptek - Destroyer Lord - Necron Lord - Necron Overlord - Phaeron|
|Troops:|| C'tan Shards - Deathmarks - Flayed Ones - Immortals |
Lychguards - Necron Warriors - Triarch Praetorians
|Constructs:|| Canoptek Spyder - Canoptek Wraith - Crypt Stalker |
Scarab - Tomb Sentinel - Tomb Stalker - Seraptek Heavy Construct
|Vehicles:|| Annihilation Barge - Catacomb Command Barge - Doomsday Ark |
Ghost Ark - Monolith - Sentry Pylon - Triarch Stalker - Tesseract Ark
|Flyers:|| Canoptek Acanthrite - Doom Scythe - Heavy Destroyers |
Necron Destroyers - Night Scythe - Night Shroud - Tomb Blades
| Abattoir - Æonic Orb - Doomsday Monolith - Megalith |
Necron Pylon - Obelisk - Tesseract Vault