Found a beautiful pic of a round cake that said it was 3 ten inch layers and a 6 inch layer on top. I am not sure what the best way to assemble and cut this type of cake would be. Has anyone done this??

Sounds like a tall cake! I would treat it like any other stacked cake - I would frost and fill as you normally would, then I would put 4 straws (or whatever your choice is) down into the 10" layers then put your 6" cake (on a cake board) on top of the 10".... you could also put one large dowel thru both cakes in the middle. Kind of the way you would assemble a wedding cake. Then when you are going to serve/cut it ... just remove the 6" and cut them separate. Do you have a picture of the cake?