>>96908859
From a collector booster, 4 cards are from TLE most of the time (1 can be a scene card from the main set 8% of the set). Those TLE cards are from Jumpstart or the Beginner Box, and there's also the chance of one for the non-foil rare.
https://magic.wizards.com/en/news/feature/collecting-avatar-the-last-airbender Check here for more details, scroll way down.