Blender has some really cool new features:
I modeled these spooky trees in a matter of 15 minutes using the "skin" modifier, which takes the vertices and edges of a base mesh and creates a 'skin' mesh around it. Scaling the vertices controls the thickness of the generated mesh, so an organic shape like the tree trunk and branches here is simple to create.
The spooky volumetric fog here is true 3D fog that you can move through, just like the real thing. It's a bit of a memory cruncher when I combine it with 5 passes for my 'HF Sketch' look... but it's worth it in the end... Have to find a way to work this into the next film ;)