An opponent can play a reaction to wake as the card is played, before its effects apply.
100513
Deed the Heart's Desire
Only usable as the action is announced.
Choose a younger vampire. The chosen vampire cannot block this action.
As above, and the chosen vampire cannot play reaction cards during this action.
Rulings
Must be played (as well as other "as the action is announced" action modifiers) before action modifiers that are not explicitly played "as the action is announced" (e.g., Conditioning).
Replace the action card (if any) before playing it.