This is the Gundam Barbatos Lupus Rex after it was partially destroyed by Dainsleif attacks.
During the operation by Arianrhod to wipe out Tekkadan, the Barbatos Lupus Rex fought as fiercely as it could, but sustained heavy damage from Dainsleif attacks launched from the orbit of Mars. Its pilot, Mikazuki Augus, was gravely injured.
However, Mikazuki refused to stop fighting, and instead bypassed the Alaya-Vijnana System's safety limiter. The Barbatos, with its eyes glowing red, fought like the demon it was named after, slaughtering one Arianrhod suit after another.