Archmagos Belisarius Cawl's duplicate, who had been stewing himself in an iron pot, slowly climbed out of the acid.
You should've said you were on our side! Scared the hell out of me.
I thought the traitors' main force had attacked.
After spinning three and a half times in the pot, dissolving thirty percent of his body, and climbing out for more than thirty rounds of washing, he positively gleamed.
The situation was rather confused. He needed to explain things in person.
He was directing the Pharos project-the Astronomican of Imperium Secundus. The original Pharos had been powered by a shard of Zahurash, Overlord of the C'tan. The Archmagos had traded with him for information on Pharos and the blackstone veins, then teleported him straight into the Necrons' home.
After that, the blackstone mining had begun.
This work was so important that he had to seek the most reliable protection available, which brought him to the protection of the Pharos device currently deployed on Mercury.
The Adeptus Custodes could teleport from there to anywhere in the galaxy, primarily to reinforce the expeditionary forces led by the nine First Founding Chapters.
As the architect of this plan, Belisarius Cawl was also under the protection of the Adeptus Custodes. Although they were rather inclined to dismantle Cawl and gather his knowledge into the hands of their own technical brethren, Cawl invoked the Custodes' first principle!
"The Emperor has faith in me!"
(Cawl had originally been targeted for possession by Thaddeus, a powerful figure in the Adeptus Mechanicus nearing the end of his life. But Cawl's mind proved too resilient, and the failed possession instead gave Cawl Thaddeus's memories. In those memories, Thaddeus had met the Emperor, who had told him, "Belisarius Cawl, you will do things that seem so utterly treasonous that