Play in the Regeneres Arena level in multi-player mode. Go to the big door with the Jump Boots in it. Get the Jump Boots. Back up slightly and jump up on to either of the little ledges on the sides of the door. Then, jump up to the gap in the wall higher up. Next, go all the way to the right. You will see a little button-like object with a picture of a person cut in half and a raptor next to him. Either shoot or hit it with your War Club. When you do this, stay up on the gap. Look below to see that the big door and the other three doors will open. Raptors will appear from them, and you cannot kill them. However, they will go after the other players. To make them go away, wait until they go back in the doors. This is useful, as the raptors kill the other players and they lose kills as if they killed themselves.