I have a character with an opponent's attachment and choose to put it on the top of my deck with the plot. Is the attachment immediately moved into moribund:discard or does my opponent have the chance to 'save' it by choosing it as his card to move with the plot?

Thanks in advance!

You're a little off on the way this card works. Starting with the person who revealed to plot, you go around the table with each player making their choice of target. Once everyone has chosen, all the chosen cards go to the top of their owner's deck at the same time . So you opponent would have the opportunity to choose the card for the plot long before it would become moribund itself for the character leaving play.

That said, whenever a card leaves play, any card attached to it is considered to be discarded as a passive effect . Therefore, there will always be a chance to save it - assuming the save also includes moving it to another card (or out of play).

Thanks, sir!