If talking about ports; if you off the ground by an inch, grass, rock, steps, or stairs - it won't cast. I have video proof that I got down on a small blade of grass off the ground and I can't even port. Edit: If you throw your spot placement up and hit a target name/title at the top it will instantly drop it on yourself. So the port did go off but on your location. Annoying at times if you throw it desperately.