Book: Crucible Arenas.
ARENA DESIGNATION: Black Shield
LOCATION: Firebase Thuria, Phobos
Codenamed "Black Shield," this decommissioned Firebase is believed to have been a key position used by the Cabal as they established their warbase on the surface of Mars. With the majority of their forces stationed planet side, Guardians have been able to claim Black Shield as a competitive training ground.
Both Shaxx and Commander Zavala have questioned the Cabal's strategy, believing that forfeiting such a strategic position may one day leave the Cabal, and Mars, open to a proper offensive.