Orthrus

Orthrus is the two-headed hound that guarded the red cattle of Geryon. Orthrus is a living guardian bred from a monstrous lineage, appointed to one herd rather than every gate of the dead. One head watches the herd while the other watches the road, making distraction difficult and retreat safer than theft.

Two-Headed Rend: Orthrus makes two 2d6+3 bites against different targets, or both against one creature carrying something taken from its herd.

Guardian, Not Pursuer: Orthrus will not move more than 120 ft from the herd or enclosure. Returning what was taken prevents both bites from striking the same target.