right, get the assault rifle and he should be at the far end of the train as he walks towards you, DO NOT FIRE, just keep him in your gun sight, he is surrounded by kryll and therefore you cannot cause any damage by shooting him (just accept) you need to wait for the kryll to fly away (this happens from time to time) and then empty your clip into his head, eventually he will get to your position so run towards the other end of the cart and repeat processhe should die in no timeone last point: STAY IN THE SPOTLIGHT, if you don't the kryll will attack you and you don't want that