From Halopedia, the Halo wiki
Ardent Hunters almost always sport red and steel coloured armour with red tinted assault cannons and eyes as opposed to the usual green. Their assault cannons have been overclocked and modified to focus unstable energies across a wide powerband, and their combat shields have been reinforced with cold-layered alloys to withstand even greater firepower than their Covenant armour would allow. Ardent Hunters are often deployed at critial security sites from artifact excavations to vital convoy routes, command barracks, and forward war councils.
List of appearances