The following came up in a game the other night.
Mage of Loec reads:
Action: Cancel an Action just triggered. Then, this unit becomes a facedown development unless you discard a quest from your hand.
What happens if each player has a Mage of Loec ? Say Player A triggers an Action, Player B then triggers Mage of Loec 's Action to cancel that Action. Player A responds by triggering her own Mage of Loec to cancel Player B's Mage of Loec . Player B then responds by triggering her Mage of Loec to cancel Player A's Mage of Loec , ad infinitum. Does this go back and forth forever?
The second sentence, "Then, this unit becomes a facedown development ..." appears not to be a cost of the effect, but part of the effect itself. If the card read " Action: Turn this unit into a facedown development or discard a quest card from your hand to cancel an Action just triggered" it would be a cost and so would have to be paid at the outset. Meaning it could not go on forever, assuming the players did not have a way to discard an infinite number of quests from their hands or turn Mage of Loec back into a unit from being a development. However, that is not how the card is worded.