The look on an opponents face when you play your first turn dark ritual followed by the hypnotic specter is priceless. They know at that moment that if they don't do something quickly the game is going to spiral out of their control. The reason for this is simple, losing a card every turn means is bad enough, losing one at random is even worse. In fact the only thing worse than losing a card at random is for you to lose a card of your opponent's choice every turn, or is it.
Shimian Specter is not going to be put into play on the first turn with a dark ritual, as a rare specter from the future sight expansion set of magic the gathering he costs two black and two colorless mana and is a 2/2 flying creature, but on the other hand if you can hit your opponent with this card just once it can become very difficult for him to ever stop you.
The Shimian Specter reads "Whenever Shimian Specter deals combat damage to a player, that player reveals his or her hand. You choose a nonland card from it. Search that player's graveyard, hand, and library for all cards with the same name as that card and exile them. Then that player shuffles his or her library."
The real question is not whether this ability is good, because it is clearly very powerful the question is what cards do you choose to exile if you are able to get through your opponent's defenses.
The suggestions may be different based on the deck but in general my suggestion would be that you begin with creature removal spells that could target the specter. Allow them to keep their terror for now, but wrath of gods have to go. Next remove flying creatures. The reason for these two choices are simply that you want to be able to use the specter against next turn.
After that go for anything that could hurt your decks basic strategy. Counterspells are of course a perfect choice, as are other creatures.
If you can hit an opponent even once with this card it can be a game changing event and a couple times can easily put your opponent into a hole he is unlikely to ever find his way out of. The only problem is that hitting your opponent with a 2/2, even with flying isn't always easy, but finding a way is worth it with a card this powerful.