"Because those four cards contain the energy of the universe. En Moon harnesses the power of the cosmos, while En Winds helps the force of storms and gale. En Birds contains the life force of all the living creatures, and En Flowers was the very power of mother nature herself." - Ray explains the power of four cards to Riley 
According to Leo Akaba the purpose of these cards was to harness the natural energy of the planet to equal and counter the malicious aspects and energies of humans that metamorphosed Z-ARC into his fiendish draconic form, effectively reverting Z-ARC to that of an infant.
Leo Akaba investigated a method to stop Z-ARC's fused form. By traveling the world and following the theory of Duel Monsters with souls while researching different natural environments, Leo was able to create four Spell Cards subtitled under the names "Flowers, Birds, Winds, and Moon" from the natural energy that he believed would be able to counter Z-ARC. Through analyzing and studying the desire of plants that are destroyed but sprout with the seasons and animals that endure winter to survive to spring he was able to fulfill his objective. The audacious desire to live that has manifested in the world for hundreds of thousands of years. This generated a robust energy that Leo hoped to utilize to halt the dark emotions and surpass Supreme King Z-ARC. However, when Leo had just finished creating the four cards, Ray stole the cards as she could not bear the thought of losing her father.
Leo gave chase to his daughter but she activated a card, destroying the surrounding buildings and blocking his way with rubble. Leo then took a different road and eventually saw Ray, confronting Z-ARC, as she activated the four cards, causing the related natural energy sources of flowers, birds, wind, and the moon to react and converge within Ray's body. The reaction of natural energies then created the Natural Energy Bracelets on Ray's right arm. The natural energy convergence then caused a reaction in both Ray and Z-ARC's bodies, and subsequently de-fused the Supreme King Dragon from his dragons as well as Ray's and Z-ARC's original bodies into four, creating their Dimensional counterparts and the Four Dimensions. The cards themselves then manifested as Natural Energy Bracelets worn by Zuzu Boyle, Celina, Rin, and Lulu Obsidian, Ray's reincarnations.
Later, the bracelets were transformed back into their original card forms when Leo attempted to reunite the four girls back into Ray. The four cards were then used by Riley Akaba to defeat Z-ARC and seal his evil spirit for good, again, manifesting as the four bracelets on Riley's right arm. While their status afterward is unknown, Declan confirmed in the English Dub that the cards perished after the battle due to having used all their power.
The Natural Energy Cards are the original forms of the Natural Energy Bracelets.
Each of the cards' names include the word "En", likely from "Energy". These cards are also likely inspired by the Japanese phrase
Natural Energy Cards' playing style starts with the game having many Fusion, Synchro and Xyz Monsters in the GY or banished. When gathered, they're activated as quickly as all at once. After all of them are activated, which would have Fusion, Synchro and Xyz Monsters' Effect negated and them treated as Normal Monsters, they are destroyed with "En Flowers" and would severely damage the opponent.
|Human||Deck||Power source||Letter symbol|
|Birds||Xyz||Lulu Obsidian||Lyrilusc||Life force||Epsilon|
|Flowers||Any||Zuzu Boyle||Melodious||Mother Nature||Pi|
|Winds||Synchro||Rin||Windwitch||Storms + Gale||Square cap|
- The Natural Energy seemed unable to separate Z-Arc and Ray's fragments a second time when Riley sealed Z-Arc's soul within herself. Yuya and Zuzu revived in place of Z-Arc and Ray, with the other fragments's souls within them.