Cactus Game Design Message Boards

When an artifact has a limit do you get to pick when it is used, or does it have to be used the first time it is activated?

Examples:
Thirty Pieces of Silver "Regardless of battle outcome Hero is discarded.  "David's Harp" has no effect.  May be used twice."
Ark of the Covenant "Regardless of battle outcome, one Evil Character an opponent uses to block a rescue attempt is discarded at the end of battle.  Limit holder to two such discards per game."

Ok so if I activate Ark of the Covenant, and I'm playing in a multi player game, then the next two battles the evil character is discarded, and I won't be able to change the artifact before it is discarded because it will be used both times?