What im saying is that the Dragon simply told the Emperor about the Dolmen Gates, learning about the webway and setting out to replicate their feat of travelling the network to avoid dependence on warp travel.
It wouldnt strike me as farfetched that those 2 powerful beings made an awful deal. In exchange for the knowledge of the ancients. The Emperor would move the dragon to Mars, so it might influence the civilization that would come to grow there as he had foreseen. The dragon getting them as its playthings for a brief cooperation with him.
The dragon, or at least a major shard of it would need time to grow and mature, happilly suckling up the cast off life from the mechanicum adepts as they strove to become closer to their cold ideal.
Edit: Regarding the War in the Heaven. Its easy enough to explain. The full power Cthan would litterally be pushing the necron ships across the universe in the blink of an eye. But after their rebellion, using the Dolmen gates was the only 'reliable' method of transportation they had left. Now that the Cthan's power had been broken.
Last edited by Brother Lucian; 05-27-14 at 08:46 AM.