Expansions consist of a variety of components which may or may not be used according to the current scenario.
We include all standard components from each expansion in every game. This means all of the following:
- Non-sideboard locations
- Mythos cards
- Playable characters
- Unique Assets
- Great Old Ones
- Epic monsters
- Focus/Clue/Health tokens etc.
Regarding clue tokens or gates that are for a side-board not in play, we leave them in the game and if one is drawn, simply draw another. I find that is easier than sorting them out but do as you wish in that regard. If you do wish to remove a specific expansion, the cards have a small indicator on the front side of which expansion they are from.
Sideboards come into play in one of two ways:
- When a GOO is chosen that requires the use of that board, or
- When a prelude is chosen that requires the use of that board.
Mysterious Ruins are the same as sideboards. The are present when playing against the Syzygy GOO, or when drawing/choosing the Cosmic Alignment prelude.
This means that generally you will only have one of the sideboard/ruins used during a given game, and then you will include cards specific to the locations on that board, or the mystic ruins deck (from now on, when I say sideboards, include the mystic ruins deck as it is bought in to play in the same manner)
It also means however that multiple sideboards may be used when playing against a GOO that requires one sideboard, and starting with a prelude that requires the other sideboard. For instance one could choose to combat The Elder Things from the Mountains of Madness expansion, while drawing the Museum Heist prelude from Under the Pyramids. There is no official statement regarding extra rules here as far as I am aware. I have not tried it but I suspect for small player counts you would find it difficult to cover all the ground. If you want to make it easier than you could use the variant reference cards mentioned here.
There is no official way to play with both sideboards and ruins, however you could do so by allowing two preludes concurrently, eg: GOO = Nephren-Ka, Prelude1 = Antarctica, Prelude2 = Cosmic Alignment.