It is not 12.5 EPA simply due to the rather obscene Nightmares cost. You would spend God knows how long getting out of the Mirror-Marches or the Royal Beth. The only way I can possibly think of how one could dodge this penalty would be to do this during Christmas and then have like 10 alts spam Nightmares-reducing Christmas Cards at you since that doesn't require you to accept the action, you would have to be very careful about positioning your ex-seeker though, the instant it says that your character is back in the London setting though, clicking onwards from the storylet which got them there will shunt them off to madness, so you just have to park them there and forget about doing anything with them until said spamming is done.