Please FCS Help Me Find The Name Of this movie!

Hi everyone!
Ok i'll get to the point.Before 9 years i saw a Horror movie in a local channel.Let me tell you some things about the plot.
Ok,so there were some guys (i think 3 guys and a couple of girls) and the guys decided to scare the girls at the midnight in one house which was near a lake.Yeah,so they made a fake monster and scare them,but after that a real monster came out of the lake that was searching for a necklace (i think it had to do something with the moon).From what i remember the monster went into a building and the movie ended with a police report saying that the "so Called" zombie was a chained man who was dropped in the lake.

The Movie had black/white colors.This movie means a lot to me because that was the day that i bought my first Heavy-Metal Album (best of the beast) and i spent the rest of the night hearing to Iron Maiden with the memories of that great movie..

So if anyone could help i would be thankful!!!