[Mercury Shadow]

I really don't understand why everyone is having a hard time with Vamp, I though Fatman was 10x harder! But anyways, he isn't as easy as Olga... First of all, get your favorite automatic weapon, whichever has the most ammo, and then shoot out the lights up top (I didn't do that, but everyone says it's good), and you should always shoot him will he's swimming in the water or throw grenades in the water. Just be on your guard and don't get too close to the water.