why are some of my objects rendering as a dark blue? I'm making a project for my art class but for some reason 2/3 objects in my preview will not render. Does anybody know why? Its the terrain that will not render
For the dragon and other objects, you have their children objects disabled from render, as you can see in the screenshot:



For the terrain, it is related to materials setup (nodes), especially try to fiddle with your alpha handling, I am not sure what are you trying to achieve there -
it would be easier to if you pack textures into the .blend and re-upload it.
I will try to correct it and then update the answer.