It says:"Response: After a character's STR is reduced to 2 or lower by a card effect, return that character and all attachments on it to their owner's hand."

Now my Sellsword Deserter comes into play, four characters' STR reduced to 2 or lower, then how many characters return when i play the Pyrophobia?

I think it should be only one. But my friend perseveres in it should be four.Who is right,and why?

You are right, because the card is responding to a specific trigger; in this case, a character's STR being lowered. All four characters produce a separate trigger, so that if you were somehow able to play the card four times within the same response window, you could return them each to the owner's hand.

Repost this on the rules forum. While the card text is ambiguous enough to allow for multiple characters to be returned, I do not believe that is how it would be ruled. Ktom probably should weigh in on it.

mdc273 said:

It is not. Every character being reduced offers a Response opportunity, that's true. But Pyrophobia talks about "a character" and "that character". Clearly, each Pyrophobia can return exactly one character back to hand. In order to return more than one character after Sellsword Deserter enters play, you need more than one Pyrophobia.