I know the warp houses all the psychic and emotional energy created by all the psychic races in the galaxy, and that energy taken to the extreme by the nature of the warp caused the emergence of all the daemon, dark gods and other warp entities that plague the galaxy.
But what about benevolent entities? Beings shaped in the warped by the more positive emotions the races posses. It is theorized that the Sanguinor is one such entity of the warp, that helps the blood angels in times of dire needs. And is thought to be the embodiment of the emotional and spiritual need of the chapter's desire to see their Primarch reborn. But what about other long dead primarchs or even the Emperor? Surely the belief and adoration of the Imperium towards the Emperor would have some impact on the warp.