Do [damage: 20] to two disengaged enemies of HP1 or higher. Return any unit hit of HP 0 or below to the File. You get 2 less SP at the beginning of next turn.
I dont really know if this is right or not, but i interpret 3rd sentence as "you still get 2 less sp next turn even if you fail to return anything" since there's no "then" clause. I fought Harvest today, and after the ss activation -which is failed because all my units are engaged- he still get the 2 sp next turn. I forgot to to record the battle id.