Whats the best way to "merge" objects like these Im new to Blender and i am having problems with trying to "merge" these objects, whats the best way to do it. Its for a game so just putting them together would waste tris if i understand everything correctly (Since there will be faces inside the object)
Cleanest way I know:


Add three loop cuts to the blocky object in both directions.
Delete the four middle faces
Snap the vertices to the octagonal object.
go to Object Mode
join the objects
Remove doubles