Have you ever thought that it takes too long to get the opportunity to sell your souls to eldritch horrors?
These civics allow you to start the game with any of the five shroud covenants. As a bonus, some of your leaders will become psychic, and the chance is higher if you also have the latent psionic trait.
If you take Covenant – End of the Cycle, you can delay the Reckoning by sacrificing planets. Each planet buys you one year, but also makes the End of the Cycle stronger.
The consequences of the various covenants are almost entirely unchanged, though it is worth pointing out that the Eater of Worlds cannot eat your homeworld. A few 2.3 bugs with the End of the Cycle have been fixed, and the exiles now have their own unique civics to make the probably-still-doomed struggle more interesting.
The regular four covenants can be selected by AI empires, but the End of the Cycle cannot.