This card is so versatile, everything ax4jim says in the previous review is correct. This card helps cycle through your deck, which if you are running 6s as one of your stronger values, is amazing.
The best way I found to approach this card during deckbuilding is to imagine that it doesn't even actually exist. If your deck can do what you want, your draw structure is incredibly tight, some 6 value cards in your deck won't hurt anything like skill pulls, and you have 1-4 slots to fill, this card is perfect. It's either invisible in your deck, or an uber reserves if you get lucky and happen to need ghost rock. This is probably the most widely playable card in the game right now.