The Undertow

You can't have a second copy on board.

In your own watch, while this card is in your scrapyard, you may pay the cost to put it on board. It isn't deployed: no one can react to it. It comes on board new.

Not when you deploy it: it happens once it has resolved and is on board, after your opponent's chance to react. Put on board without being deployed, as by Resurface, it happens too. In the sortie phase it goes into the crossfire (301.10). Choose a crew on board when it happens, either player's, not this one; with only one to choose, it goes, and with none, nothing happens. The crew goes back to its owner's hand: it isn't destroyed, and it loses its damage, markers and bonuses. A token stops existing (801.12).