Lets suppose someone, who shall rename nameless (but has really great hair), was fully stuck on the old 2nd Ed MW:RPG system and never bothered to move to 3rd Ed because...well she was quite comfortable with the simplicity of MW2ED. Now that ATOW has come out, one wonders if this is a compliment to 3rd Ed or (effectively) 4th Ed MW:RPG?
In other words, do I need to buy 3rd Ed to make use of ATOW or not?