The Altar is a pocket universe created by Legion that exists in his head and allows mutants access through Krakoa Gateways. The Altar is connected to the Astral Plane but is not part of it: visitors physically exist inside David's head and any danger to him poses a danger to them as well. Separate areas of the Altar are Qortex Complex in which Legion stores his personalities, the Beach from which the Astral Plane can be directly observed and the Congregation, a visitor hive mind maintained by Dust.[2]
History
Having organized his brain into pocket universes in the past, Legion had done so on purpose for the first time during Onslaught's attack on Krakoa. To be able to converse with his allies in secret and remove Onslaught's influence from those affected, David created inside his brain a boundless psychic space that bridged the physical reality and the Astral Plane. A seed planted directly into his brain connected the Altar to physical reality through Krakoan Gateways, the first of which was the Temple Gate on Arakko.[3] Mutants affected by Onslaught were brought inside the Altar, where they could be safely removed from his influence.
After the Onslaught crisis had passed, Legion opened the Altar to visitors, creating a place for creativity, training, healing and more.[1] All mutants could visit via the Gateways, while teleporters could access it directly to its set physical location inside David's brain.[2] Kurt Wagner also used it as a base for his new Legionaries.[4] While the Altar was accommodating to organic life, some laws of physics were flexible: visitors could individually control their own gravity while some such as Warlock manifested in a form different from their regular appearance.[5]
