There is no Max full composition node, but it's very easy to create one using component:
Get the attached Max full composition.terralib file, which is an Instant Terra component library file.
Drag & drop it in the Instant Terra window.
This will import the component and insert it in your project.
The new node will appear in the Models window on the bottom left, inside the Component library category.
You can now use it as any other nodes.
You can see how it's done by right clicking on the node in the graph and selecting Edit component.
You can create another component with a Min node instead of a Max node, etc.
You can also change its color and put it in the Terrain composition category if you want.
