Additional Rules
Face-Down Cards
Cards that have been played face-down but have not yet flipped are unaffected by other card abilities unless the ability explicitly states that it affects face-down cards. For example, a face-down card cannot be destroyed by the ability of Cthulhu - Wrathful Cosmic Entity.
If a face-down card is on a hex that its controller loses control of, it is not destroyed and will flip as normal.
Moving
Whenever a player moves a card, that player may also rotate that card. The card must move from one hex to another hex in order to rotate. If a card "may" move, the player may choose whether to move (and therefore, potentially rotate) the card, or to leave the card in the same hex and same rotation as before.
Sometimes a card may move to a neutral hex or an enemy hex. In this case, the card is not immediately destroyed. See "End of Turn" for more details.
End of Turn
At the end of each turn, if a card is on a neutral hex or a hex with enemy influence on it, that card is destroyed. Place it into its owner's discard pile.
Triggered Abilities
Sometimes, a game action will cause a card's ability to occur. This is called a triggered ability. In these cases, the game action that caused the triggered ability will finish in its entirety before the triggered ability will occur.
For example, if Caligula destroys Frankenstein's Monster with his post-attack ability, Frankenstein's Monster will be placed into its owner's discard pile. Next, Caligula will add 2 influence to Frankenstein's Monster's hex or his own hex. Then, now that Caligula's ability has completely finished, Frankenstein's Monster's triggered ability will occur.
Destroy vs. Discard
In F&F, "destroy" and "discard" are separate game actions, even though they both result in cards being placed into the discard pile.
Destroy: Cards on the board can be destroyed. This happens if a face-up card is on a hex that is reduced to 0 friendly influence, when a card is "destroyed" by a card effect, or during the end of turn phase.
Discard: "Discarding" occurs only when an effect tells a player to do so. The word discard is often used for discarding cards from zones other than the board — for example, a player could be forced to discard a card from their hand or the top card of their deck.