Is There a Way to Combine Instanced Meshes For Calling?

Is there a way to combine several meshes into one, and then call that mesh as an instance, rather than a static mesh? For example, could I combine a sphere and a cone and then call that specific mesh any number of times as an instances mesh?

What is the best way to do something like this?

My ultimate goal here is to be able to create a specific dungeon room that can be called multiple times but in different locations, kind of like some of the boss zones in Diablo 2.