Answer:
Weight in my belly trees on my back nails in my ribs feet I do lack.
I may seem real but it always turns out I was never there in the first place... you only see me during a certain resting stage.
My full powers come when my makers are dead. I await a heavy hat to put on my head. What am I?
I have keys but no locks. I have space but no room. You can enter but can't go outside. What am I?
The more you have me, the less you see. Shine a light on me and I flee. What am I?
The answer I give is yes, but what I mean is no. What was the question?