Hunting Party is one of the "Power Cards" which emerged from the new Cornucopia release. The obvious comparison is to Laboratory, against which it is usually better but sometimes worse. Like Laboratory, it usually nets you +1 card (+2 cards +1action -1card and action for actually playing it). But the ability here is really key, in that it gets you a card you don't already have in your hand. This makes it look like it would combo well with Menagerie, but it can also get your hand so big, and you often want so many Hunting Parties, that the synergy is not so strong as it might be.
The cons of Hunting Party are, in addition to the uselessness of Lab when you're drawing your whole deck every turn, when there are no more cards in your deck that you don't have in your hand, it turns into a cantrip with the chancellor effect. This is still not so horrible, but not really what we're looking for in a power $5. So naturally, Hunting Party is at its weakest in a very trimmed deck and/or a deck where you have one card (especially a treasure or terminal) that you want to spam a lot. Hunting Party is also not so resilient against handsize-reducing attacks, as the cards you're dumping away are probably going to be the ones you want Hunting Party to skip over anyway, and now it won't.
On the other hand, Hunting party is at its best when you have a handful of cards that you want to all draw at once. Want to be able to play KC and Bridge in the same turn? Hunting Party is your card. Want to have multiples of each? Not so much. But generally a good Hunting party strategy is to use it to need only one of the top money (gold or platinum, depending on whether or not there are colonies) card and still be able to draw it every turn. For instance, in a non-colony game, I'll often get a single gold, an attack or useful card that nets me $2, at least one silver, and then a bunch of Hunting parties. This nets $8 pretty reliably, with an attack every turn to boot. It's important to note that in this kind of deck, every turn you get $5-$7 after you have your one Gold, you want to go Hunting party until either a) they run out or b) it's time to turn for duchies. But this is extremely powerful. Check out this game where I smash my opponent's Chapel(!) opening with a good Hunting party deck of this type, with Cutpurse as my $2-gaining terminal.
http://councilroom.com/game?game_id=game-20110610-211238-aabfd032.htmlObviously you'd rather have Militia, Monument, or Mountebank for this spot, but even Cutpurse is pretty good.
You can also play every Conspirator in a deck with pretty good frequency in a HP deck, which is a fairly good combo to have. Just remember to play your Conspirators BEFORE your HPs after they're non-terminal. It's to remember that if you do get the chancellor-effect out of HP because you have everything, you probably don't want to play that last card-drawer in your hand without another HP, as then all of the actions you've just played in your chain will miss out on the reshuffle, and your next time through you'll see only the cards you've got multiples of - your coppers, estates, and maybe silvers - without having a shot at any HPs to restart the chain.
Works With:
Other Hunting Parties
Spammable non-terminals (see Conspirator)
Fairly tight decks where you want to get exactly 1 of every card
Attacks, which it lets you play very often
Opponents' curse-givers (sort of), which it helps you sift through
Conflicts With:
Spammable terminals (see Goons, Wharf)
Opponents' Handsize-reducing attacks
Your own trashers