The Grasshopper and the Scorpion
There were two figurines in little ebony caskets on the mantel that Christine had been forced to choose from. The grasshopper would send the Opera House jumping into the air. Thats what the gunpowder was for. The scorpion, however (which was Christines choice) would result in the water from the lake coming into the little trap door room from the torture chamber and wetting the gunpowder. The water rose so rapidly that Raoul and Darius barely had time to get out. Keep in mind that they were in there for a long time..