Wasn't familiar with that actress but I hope they didn't bring her in to overshadow Seo-bi. She's one of the best female characters we've seen in any historical we've watched here. It has the smell of a ratings gimmick to it. Hope I'm wrong.
It looks like they'll be doing a Season 2.5 next year with her character Ashin as the main character, showing how she survived during the timeline of Season 1 & 2. They're doing this because the main cast of Season 1 & 2 are busy doing other movies or dramas for the time being.