When I talk about getting cards, I'm referring to what your deck looks like at the end of the game, and the ways that those cards got to your deck in the first place.
I find it interesting that before Adventures, there were only 2 possible ways to get a card: Gain it, or be passed it via Masquerade. I'm not missing any, am I?
But Adventures adds not 1, but 2 new ways to get cards. The exchange mechanic, which puts a card in your discard pile without gaining it, and Inheritance, which gets you a card that you can't actually use, without gaining it. Though that card can't ever be in your deck during the game, it DOES count as being in your deck at the end of the game, for Gardens and Fairgrounds.
*Edit for the full list*:
Gaining
Passed via
MasuqeradeExchanging
Returning
Fortress to your hand after trashing it (and also with via
Lurker you can get one without having ever gained it).
The card you set aside via
InheritanceReturning trashed cards do your discard pile via
PossessionExiling a card from the supply with
Coven