Riddonkulous

Now I am such a fun thing! I have so many uses, it's enough to make you sing I'm a dart, a start, and even a dash I can arrive in a flash, a clap of thunder to herald my arrival If you need lots of cloth or paper, you'll find plenty of me and I won't be a trifle I can be a gatekeeper, as long as you hold my key I can even help you fight or flee