The Shadow Council is a secret organization with connections to the Abyss (a mysterious entity which is said to power the Ultimate Nullifier). Recruitment seems to involve being taken into a timeless space outside reality and having something explained to you by entities referred to as "the ultimate sore losers"; from context, these entities lost a conflict with the Celestials and were excised from reality as a result. Their plans are vaguely understood, but will somehow result in the destruction of civilization sometime in the future.