A gigantic cybernetic spawn from Hell, the production of a tank's chassis fused together with the torso of Sergeant Kelly, along with a gigantic Metal Claw and the BFG 9000 (Big F***ing Gun). This is the third of four bosses in Doom 3, and uses a variety of attacks to attempt and kill the player.
These include ---
* Running over the player * Firing the BFG 9000 at the player * Swinging the mechanical claw at the player * Forcing the player to take shelter near nearby pillars in the arena, which electrocute him * Causing the player to fall into the pools of larva underneath the arena, resulting in an instantaenious death.
Best bet at this guy is to grab your rocket laucher and fire at him as soon as the door opens where he enters from, then as he drives towards you to run you over or swing the claw at you, throw a grenade in front of him, or grab the chainsaw and hack away, avoiding the above two (probably painful) encounters.