whats in your head................a skull
wow hate to SPAM!
*coughinformsmoderatorscough*
skulls are pretty bad for you unless you are an absolutely brilliant player (for the most part). i've got most of them, and except for the envy skull, they make the game harder. for example, the famine skull removes half the ammo from all your guns. you need to be on legendary to be able to get all of them, except the one shini mentioned. so don't get any of them until you can aim like a god, and walk through all the levels on legendary blindfolded. when you can do that, you can worry about the skulls