There are very few ways to actually lose energy counters outside of spending them, but it is possible with stray cards like Suncleanser and Final Act
Other scene cards are found in a variety of packs and boxes
As, across eBay, even copies of the same card have been selling for dramatically different prices

Most valuable cards in Avatar: The Last Airbender View the full price guide $3,156.25 Avatar Aang // Aang, Master of Elements Avatar: The Last Airbender $671.56 Toph, the First Metalbender Avatar: The Last Airbender $517.23 Aang, Swift Savior // Aang and La, Ocean's Fury Avatar: The Last Airbender $439.14 Fire Lord Zuko Avatar: The Last Airbender $394.56 Katara, the Fearless Avatar: The Last Airbender $104.03 Wan Shi Tong, Librarian Avatar: The Last Airbender $95.74 Badgermole Cub Avatar: The Last Airbender $58.35 Badgermole Cub Avatar: The Last Airbender More cards by Dominik Mayer $3,111.74 Mana Crypt Special Guests $1,699.49 The Aetherspark Aetherdrift $1,036.46 Mana Crypt Special Guests $533.99 Mana Crypt Special Guests $377.10 Zada, Hedron Grinder Multiverse Legends $354.76 Mana Crypt Special Guests $323.50 Get Lost Spotlight Series $289.97 Mana Crypt Special Guests SetAvatar: The Last Airbender Most valuableTop 100 Magic: The Gathering cards You might also like...

The designers focused on the end goal of allowing fans new and old to enjoy seeing their favorite characters come to life on the table, and with this goal in mind, it's hard to say they missed the mark with how many truly excellent and exciting cards are coming with this release