Welcome to Librarium Online!
Where can i learn of this 4th C Tan? and of this the Dyson sphere? could someone please explian or tell me where i can find the info please?
In truth, there is little available beyond theory. I don't know where/if the Outsider is mentioned by name in the Necron codex, but the most direct reference is on the last page in the back, where you see all the notes from various transmissions, journals, etc.
In one, there's reference to a tyranid hive fleet that inexplicably has split in two to go AROUND a sector of space. Long-range scanners have picked up a massive spherical object there, and it's no big leap of logic to conclude that's what the nids are avoiding. Just what it is, well, that's not said, not in the codex anyway.
Absent other cited references, I can only assume anything further is pure speculation, but many fluff experts know that the Outsider has, in fact, been mentioned as the "fourth C'Tan" (again, not sure where this comes from), and many speculate that the orb mentioned in the codex is, in fact, a Dyson Sphere, and the Outsider is inside it.
Now, whether this is true, we don't know, and even if it is true, we don't know why. Did the Outsider built it as a haven, or was it built to imprison him/her/it? That remains a mystery.
Your best bet to finding The Outsider, and his Dyson Sphere is on the inside back cover of the codex. I don't remember where else they're mentioned in the codex tho...
The rep button () is your friend!
Be off-topic and visit www.theopia.com
Space Wolves (500) 6-0-3
Check out the fluff section here on LO and try looking there for info. If you wish you may post this there but be ready for lots of people contributing their ideas/theories/etc. If you want more on the Dyson sphere search for it on Google. But overall it's something like a Halo ring except instead of being like a circlet/bracelet you have made a sphere and placed a solar system inside. You would simulate day and night using a smaller one with holes that is around the sun. It's actually a rather neat idea.
As stated above the two main ideas is that either The Outsider built it for some unknown reason or someone imprisoned The Outsider there. As for the second it's most commonly thought that it would be the Eldar who did so because of their tech. Of course their reason for doing so or if they even did is unknown. I hope this helps.