The wonderful Evanna Lynch (aka Luna Lovegood in “Harry Potter”) comes back to the podcast for “Appa’s Lost Days!” Janet and Dante can’t imagine a better guest to weather the heartache of this crucial and unique episode of ATLA, when we find out what happened from the moment Appa was taken away as Toph struggled to keep The Library from sinking in that eponymous episode. How many tissues will it take to absorb our tears as we talk through Appa’s entrapment, horrible treatment, brave escape, and reunion with a gentle and much-needed friend? Get your own box of tissues ready, and find out!