SIVA

The SIVA plague was once a Golden Age breakthrough in self-assembling, self-replicating nanotechnology. It was discovered by the Iron Lords and during their attempt to aid themselves in protecting humanity, the SIVA technology turned against them. Unable to destroy the techno-virus, the Iron Lords sealed it beneath the earth. A year after the Taken War, the Fallen House of Devils managed to unearth SIVA, and while their Splicers tried to harness the technology the Fallen House of Devils became mutated. Unable to defeat the mutant Devils on his own, Saladin began seeking out Guardians to help him form a new generation of the Iron Lords to end the threat of SIVA once and for all.

References

https://www.bungie.net/en/pub/RiseOfIron https://www.youtube.com/watch?v=EFTn6jQk338