Book: Cabal Command.
Martian battlefield reports note that Valus Tlu'urn's weapon of choice is a back-mounted Arc cannon. The device delivers a payload so powerful the Vanguard estimates Tlu’urn could face a Goliath Tank himself. The Valus carries recharging Arc cells that feed energy to the cannon, allowing him to siege enemy emplacements indefinitely.
Reports suggest he is commanded by Primus Ta'aun and shares battalion duties with Valus Mau’ual. Together, this Cabal triumvirate is responsible for the deaths of countless Guardians on the Martian battlefields.