So Visery's text reads: Interrupt: When Viserys leaves play choose an attachment and discard it from play. From the rulebook a duplicate has the text:
card. (Cannot be canceled.)
The text for Interrupt reads:

Best Answer istaril , 11 August 2015 - 05:50 PM
Note that the word "would" on saves ("Would leave play/be killed/be discarded") indicates a timing priority. This is actually one of the trickier technical aspects of the rules, but I recommend you check out the Q&TR on this very subject. In essence, by the time you get to using an interrupt to actually dying/leaving play, you've already forgone the opportunity to save - and if you DO save, the character won't get around to dying/leaving play.
It sort of looks like this.
Effect Would Initiate (A cancel happens here, and if it does, we stop here)
Effect Initiates.
Effect Would Resolve (A save happens here, and if it does, we stop here)
Effect Resolves (an interrupt to the effect resolving happens here, but resolves before the effect it's interrupting).
So Visery's text reads: Interrupt: When Viserys leaves play choose an attachment and discard it from play. From the rulebook a duplicate has the text:
card. (Cannot be canceled.)
The text for Interrupt reads:
It's B. Viserys would leave play until after the effect goes through. However, if you save him, then the effect doesn't really complete.
Note that the word "would" on saves ("Would leave play/be killed/be discarded") indicates a timing priority. This is actually one of the trickier technical aspects of the rules, but I recommend you check out the Q&TR on this very subject. In essence, by the time you get to using an interrupt to actually dying/leaving play, you've already forgone the opportunity to save - and if you DO save, the character won't get around to dying/leaving play.
It sort of looks like this.
Effect Would Initiate (A cancel happens here, and if it does, we stop here)
Effect Initiates.
Effect Would Resolve (A save happens here, and if it does, we stop here)
Effect Resolves (an interrupt to the effect resolving happens here, but resolves before the effect it's interrupting).