She is a buxom, voluptuous brunette that lacks speed and power to be serious opposition to the main character Phoenix.
In her first scene she attempts to bully the captive Phoenix, but is quickly pressed up against the wall and told by Phoenix not to fuck with her. Later on she is seen enjoying the fighting and deaths in the Gladiator Arena. She is then called on to battle Phoenix inside the arena, armed with an axe she tries to kill Phoenix but ultimately fails. Phoenix ends the fight by knocking Mohawk out with a kick to the head, before killing her with her own axe, much to the delight of the sadistic Arena Announcer.
Mohawk's death isn't shown on screen, nor is it shown what killed her, just that it was via one blow with an axe.
Karen Russell also played the evil Chula in the 1985 movie Tenement.