Can be used after a block attempt fails (after declining to block).
Change the target of a bleed
Rulings
Must be used before action resolution, ie. before any modifier or reaction played "as the action/bleed would be successful" are played. It cannot be played after a Spying Mission on the vampire triggers.
Cannot be used to direct a bleed to a Methuselah who would be an invalid target for a bleed.
Cannot be used before all blocks have been declined.
No blocks can be attempted if it is canceled as it is played (as blocks have been declined) unless another effect subsequently changes the target of the bleed.