Astor Trio is the foundation for this effect which we have come to call the "Trio of Terror".
I think with most magicians they would like to use strong effects that they are familiar with at Halloween (as opposed to new effects that they have to learn) so we are trying to come up with idea's on some of these standard props so that they can be "spookified" so to speak for Halloween shows. Astor Trio is a perfect candidate for this type of conversion because you can use any poker style deck of cards and there are plenty of spooky poker style decks of cards available on the market. My favorite is the Tragic Royalty deck and Toys R Us also makes several spooky decks that can be ordered online as well. Since the bulk of Astor Trio is a frame displaying 3 cards the idea is to make those three cards spooky looking and you have a very spooky looking effect.
Another idea is to use 3 different decks of spooky cards, have 3 spectators shuffle each deck, then have each spectator hand back one card face down from each deck and put them in the Astor Trio frame and reveal the predictions.
As far as the Astor Trio prop is concerned, it is, in my opinion, a great investment and you will not be disappointed with it. In fact, you will be amazed how easy the effect is to do. No skill required so you can concentrate completely on presentation. Setup takes a little longer than it takes to write out your predictions (it uses dry erase markers so predictions can be different colors if you like) but writing the predictions will be the longest part of the setup.
Astor Trio does have a few limitations, it cannot be performed surrounded and bridge size cards will not fit properly in the slots to hold them. Other than that it is close to being a perfect effect and is highly recommended.