Answer:
I am always in front of you but you will never see me
In a tunnel of darkness lies a beast or iron. It can only attack when pulled back. What is it?
Goes over all the hills and hollows, Bites hard, but never swallows.
I am like thunder in your cranium
You hear me speak, for I have a hard tongue. But I cannot breathe, for I have not a lung. What am I?
I go in hard, come out soft. Blow me hard and I'll make a pop. What am I?