<meta property="og:description" content="http://www.tvinsider.com/article/73721/11-things-to-know-about-once-upon-a-time-100th-episode/Over the course of 99 episodes, Once Upon a Time has flown to Neverland, stormed into Oz, quested in Camelot and gotten frozen in Arendelle. But for the series' milestone 100th outing (and also the midseason premiere), creators Edward Kitsis and Adam Horowitz are heading to the most intimidating realm yet: the Underworld. We caught up with the executive producers to find out what magic they’ve got up their sleeves for the monumental occasion—and whatever morsels they’d give us about the rest of the season."> <meta name="twitter:description" content="http://www.tvinsider.com/article/73721/11-things-to-know-about-once-upon-a-time-100th-episode/Over the course of 99 episodes, Once Upon a Time has flown to Neverland, stormed into Oz, quested in Camelot and gotten frozen in Arendelle. But for the series' milestone 100th outing (and also the midseason premiere), creators Edward Kitsis and Adam Horowitz are heading to the most intimidating realm yet: the Underworld. We caught up with the executive producers to find out what magic they’ve got up their sleeves for the monumental occasion—and whatever morsels they’d give us about the rest of the season."> TVInsider Feb 22: 11 Things To Know About OUAT's 100th Episode - Once Upon a Time podcast forums