Answer:
I am one small little piece of paper yet sometimes hold lots of value. I am all you need to get in to big events but will cost you. I am an important part of travel. And if lost you're not coming.
I have roots nobody sees. I am taller than trees. Up up I go but I never grow.
I am your most powerful weapon; I come before your eyes. I help you seek the truth, yet I often give you lies. What am I?
A single syllable do I claim black was my most famous name; Fetal to mortals here below thousands have I slain in a single blow.
I am an object which is used in baseball. During the day I can't be seen at all. What am I?
When is it bad luck to see a black cat?