The Crimson Path is part of a strategy that Abaddon the Despoiler plans to accomplish with his Thirteenth Black Crusade. His goal is to conduct a massive campaign to breach the barriers of the Cadian Gate in order to shatter the protective fields projected by the Pylons that hold back the tides of the Eye of Terror. Once destroyed, Abaddon's Daemonic allies would be able to manifest into realspace as the Warp spread outwards, across a trail known as the Crimson Path. The expansion of the region of Chaos space would eventually spread into the Segmentum Solar and in time would engulf Terra itself. Once accomplished, even the Daemon Primarchs would be able to enter into realspace. Several Traitor Legions as well as Renegade Chapters are working to accomplish Abaddon's ultimate goal.
In truth, the Crimson Path has been Abaddon's ultimate objective. Every Black Crusade has in part been launched in order to destroy various Pylons across the Galaxy, but Abaddon has been very careful to conceal his true purpose from the Imperium at large.
- 1: Codex: Chaos Space Marines (6th Edition), pg. 20
- 2: Codex: Chaos Space Marines (8th Edition) pg.16