For a grooms cake, how do you get the look that chocolate is drizzling just over the edge of the cake?
I did a wedding cake similar to what I think you are asking....you can check it out in my photos just to be sure, but here's what I did.
I made a chocolate ganache (I use the one from the Cake Bible). Let the ganache cool a bit, but not to the point where it won't pour. I refrigerated my cake after it was iced to be sure it was good and cold and would hold it's shape with the warm ganache. Pour the ganache on the top of the cake and spread around. As you get to the edges of the cake, use your spatula to push the ganache over the edge. Do a little bit at a time so it has time to stretch out down the cake. After I was done, I refrigerate again to stiffen all the ganache in place.
Hope that helps!
You can also miz a bit of shortening to melted chocolate--that will thin it down. Pipe the chocolate mixture on the sides until it drizzles. Consistency is the key.