Before you enter the room with the beast (at the checkpoint), take out all of the enemies in the room, then on the ground floor. Pick up the health and armor at either ends of the room. Go upstairs and turn right. Follow the landing around to the end to pick up some very powerful plasma grenades. Then, go into the room at the top of the stairs to face the tank creature. This beast spawns exploding worms from its rear. Remain close to the pillars to avoid being incinerated by the spreading explosions. As for the beast, aim your explosives and guns at the weapons it is packing on his back. These include lasers, machine guns, rockets and others. At any opportunity you get, throw the five plasma grenades you have and try to get them to stick to the weapons that have not been destroyed yet. These do a lot of damage to the beast. Keep hugging the pillars for cover. After awhile, you will have most of his guns. Do not aim for the organic parts of the creature, as it takes no damage. When it is defeated, you will meet Jacob Crow again.