In the room with the obelisk you will notice that there is a stained glass window. You can break it if the obelisk falls on anyone who walks underneath it set up a spring floor board 2 spaces away from the obelisk splatter and then run over to the yellow diamond in the corner by the door. DO NOT TOUCH IT YET spring the floor when the person is near it and send them under the obelisk while the obelisk is still down rum through the yellow diamond an iron peg should be released if the peg is shot at the right time it will hit the window and shatter the glass....the glass will impale anyone near it....instant kill.