From Halopedia, the Halo wiki
A shrine-core is an irreplaceable artifact that has been retrieved from various Forerunner machinery and integrated into various Covenant warships by Huragok engineers. Extracted by Covenant exploration and recovery teams, little is known about the inner workings of these machines. The Varric-pattern heavy cruiser is equipped with an array of shrine-core power plants to provide energy to its control and weapon systems.
- ^ Halo: Warfleet, page 65, Examiners