Beat cake mix, water, oil, and egg whites in a large bowl with an electric mixer on low speed for 30 seconds. Scrape down sides of bowl and beat for 2 minutes on medium speed. Divide batter equally between prepared cake pans.
Bake 8-inch cakes and 6-inch Bundt cakes in oven for 35 to 40 minutes and 10-inch cakes for 45 to 50 minutes, or until tester comes out clean. Remove and cool completely.
To assemble, use a serrated knife to slice off the tops of the 8 and 10-inch cake so the surface of each cake is flat. Place the cut tops into a large bowl and break up to from large crumbs. The crumbs will be used a "lava rocks" at the base of the volcano. Slice the bottom off the 6-inch bunt cake so it sits flat.
Spread a thin layer of chocolate frosting between the 10-inch cake layers and stack. Spread a thin layer of chocolate frosting between 8-inch cake layers and stack. Place another thin layer of frosting on top of the 8-inch layer cake and place the bunt cake cut side down on top. Place a dollop of frosting on top of the 10-inch cake and carefully, place 8-inch cake on top and center of 10-inch cake.
Use a serrated knife to trim edges around the tops of both cakes to create a cone shaped cake. (Make angled cuts downward and leave a round base on top for icing to "flow" from.)
To decorate, frost outside of entire cake with remaining chocolate frosting. Place the cake crumbs around the base of the cake. Pipe green icing around the entire bottom of the cake for "grass". To create "flowing lava" pipe red icing a quarter from the top of cake in downward strokes to the middle of the cake with ribbon tip. Repeat technique with orange icing, starting almost at top of cake and ending where red icing begins with slight overlap. Repeat technique with yellow icing starting at the very top of cake and overlap orange icing. Drizzle yellow and red gel coloring around the very top of cake.
For the smoke effect place a few pieces of dry ice into glass candle votive. Place the votive into the hole of the bunt cake. Pour a small amount of warm water into the votive and watch it smoke.