A Portal is a Necron starship weapon system that is mounted on Cairn-class Tomb Ships, Scythe-class Harvest Ships, and Jackal-class Raiders.
Portals are vast stone gateways located within a Necron warship that act as extradimensional conduits for boarding enemy vessels.
More precise than conventional Imperial teleport technology, they are most commonly used to flood enemy starships with a relentless host of Necron Warriors and swarms of Canoptek Scarabs.
- Battlefleet Gothic Armada (Specialty Game), pg. 73