The new codex for the Grey Knights is out, and it tells the Terminus Decree. I read about this right before the License to Buy a Pizza thread, so all I could see was Orks. Apparently the decree says that if the Emperor stands up from his throne, is reincarnated, or ascends to godhood, the grey knights must stop this. There's hints that the emperor is already reborn against his will, and doesn't even know what or who he is yet. So a new story is building up.
I haven't found any news about it, only YouTubers and random reddit threads. This is coming at the same time that Space Marines are no longer male.
I guess I should mention this is WarHammer 40k stuff.
No, it is just a shard, as it has been confirmed there are not intact C'tan left in the galaxy. But at the same time, a shard of a C'tan is still absurdly powerful even in their nerfed state. To give an example from one of the more modern books, in the Pariah Nexus (where the big Imperium vs. Necron war is currently going on), an Inquisitor and their team managed to fight through a bunch of Necron's and release what turned out to be a shard of a C'tan. The shard they released then teleported them back to their ship, and basically told them "Hey, you guys are alright. I will give you one for free to make us even." And then with a wave of its hand, it killed almost every Necron on the planet (where the Imperium had been losing just before that), and then the Shard fucked off into deep space never to be seen again. Although they are very much impossible to pin down their motives, so that one escaping probably is a bad thing.
At their peak, they were literally able to manipulate reality, so it is probably for the best they got nerfed.