I love the spell Shadow Projection from the APG. It's got a great feel to it. It's wonderfully spooky and alien, something straight out of a Ray Harryhausen film. But I have to wonder if it's too powerful.
Consider an 8th level arcane spell caster who picks up this spell. That spell caster gets 8 hours of being immune to non-magical attacks (provided his physical body is secured). What's to stop that level 8 spell caster from killing a CR14 Great White Whale all by himself? The Whale has no magical attacks, and the spell caster just has to slowly wear away at the Whale's 50 strength. It shouldn't take more than 14 or 15 rounds actually.
When you consider the debate as to whether or not spell casters could also cast spells while in the form of a shadow, it gets even crazier.
Thoughts?