Simple question - When playing with 3 or 4 investigators do you use the cards from just one Core to build the encounter deck and re-shuffle the discard pile after it runs out OR do you mix together the decks from 2 core sets?

I haven't seen anywhere in the instructions that says to use more than one core set. I ran a 4 man game the other night with just one core sets worth of encounters and it was fine, I just reshuffled the encounter deck when it ran out.

If the encounter deck is empty, shuffle the encounter discard pile back into the encounter deck.

This is from the "Encounter Deck" section of the Rules Reference. I think I've played it wrongly by waiting until I needed to draw to shuffle the discard, but it's pretty minor.

I notice on the product page for Arkham it says you need two core sets to play 3 to 4 players. Would you then also need two of each for the expansion packs? The reason I am the only one of my group willing to buy. I just want to make sure I have the right components for four player game.

It's just the Core Set. Everything else has a full set of player cards.

It's just the Core Set. Everything else has a full set of player cards.

It also depends on how much you want to explore deckbuilding. If you just want to tweak the premade decks from the Core Set, you can do with 2 Core Sets and 1 of each expansion for the group. If you want to really deckbuild, you'll need a lot more (or print proxies for the cards several players want).

It's just the Core Set. Everything else has a full set of player cards.

It also depends on how much you want to explore deckbuilding. If you just want to tweak the premade decks from the Core Set, you can do with 2 Core Sets and 1 of each expansion for the group. If you want to really deckbuild, you'll need a lot more (or print proxies for the cards several players want).

I would second this approach. Just photocopy cards that players would also want to share and just put the paper print outs over some other random cards and sleeve your decks. This will make everyone happy about the new cards and won't restrict them based on whether or not someone else is using those cards in their decks when they make upgrade or building decisions. There will be lots of people who will want to use the new and shiny stuff.

As far as the encounter decks, it can matter a bit with cards that tend to stay out in play. With only a single core of encounter cards, some cards will remain in play through a deck shuffle and therefore will not be available to put back into the field. With 2 cores you could have twice as many of those cards out there causing trouble to your party that you have to deal with. So I can see the difference it might provide. But, I don't know what the correct decision would be.

As far as the encounter decks, it can matter a bit with cards that tend to stay out in play. With only a single core of encounter cards, some cards will remain in play through a deck shuffle and therefore will not be available to put back into the field. With 2 cores you could have twice as many of those cards out there causing trouble to your party that you have to deal with. So I can see the difference it might provide. But, I don't know what the correct decision would be.

The encounter deck is always made with a single set of cards. The only benefit to having 2 Core Sets on that front is being able to prepare encounter decks for all 3 scenarios at the same time (each encounter set is used in at most 2 scenarios).

I can see where OP is confused, because I share the confusion. In the setup instructions for the encounter deck it says to take all the copies of the encounter cards (pg 5 of Learn to Play; italic paragraph in step 9). For Rats, there are three cards in a single core set, but if you are using two cores so you can play with 3-4 players, wouldn't you use all six Rats cards?

I can see where OP is confused, because I share the confusion. In the setup instructions for the encounter deck it says to take all the copies of the encounter cards (pg 5 of Learn to Play; italic paragraph in step 9). For Rats, there are three cards in a single core set, but if you are using two cores so you can play with 3-4 players, wouldn't you use all six Rats cards?

The encounter deck is always made with a single set of cards. The only benefit to having 2 Core Sets on that front is being able to prepare encounter decks for all 3 scenarios at the same time (each encounter set is used in at most 2 scenarios).

Dale, I'm not sure what else there is to say in response to your post. Khudzlin and others have it right, you only use one set of encounter cards, otherwise there is a chance that more than one copy of certain cards (like the Flesh-eater) might be in play simultaneously, which given that he is clearly a named enemy (even the Ghoul Priest doesn't have a unique marker) would be very odd, and increase the potential experience available to be gained from the scenario, imbalancing the rest of the campaign. In summary, you only ever use one set of encounter cards, no matter how many copies of the core box you have, or how many people are playing.

An encounter set consists of several uniquely numbered cards (the three copies of Rats each have a different number), so mathematically speaking you wouldn't have a proper set if you mashed together all cards in an encounter set from two cores.

On the other hand nothing is stopping you from trying! If it puts more ghoul priests into play at once, you're on your own (or should be, since the danger scales up with player count). But if you enjoy that sort of thing you should go ahead and double those sets