Hellp with completing David and Goliath in the challange room.
 

In this challenge you need to kill a vampire using only your submachine gun, a real crap is that undeath are all around you.. and vampire keeps hunting you down.. i just cant do it.

How is it doable ?i wonder.

Any tips ?? pls.

aim for the head :)

You can try climbing on the blue crystal thats on the right of the lever and shoot him in the head.He cant attack you while your up there.But that only worked 1 time for me and thats when I finished the challange ;)

To late for you kjdro but I post for others who may look for a solution in future.

The metal barriers that block the side rooms can be climbed. This gives you a place to heal up. If you don't object to a bit of 'camping', jump up onto the top of the barrier and tuck yourself in the corner. The Beast can't get you and you've got a point blank shot at its head :)