HistoryThe origins of the elements are unknown, but their first recorded appearance was in the hands of the sisters Celestia and Luna, who used the power of the elements to seal the despot Discord in stone. Ironically the next time the element’s power was needed was in a battle between Celestia and Luna, now transformed into the genocidal Nightmare Moon. Celestia was unable to redeem her sister and was forced to use their power to seal Nightmare Moon within the celestial object she was named after, this apparently the last time she used their powers.
The next appearance of the elements occurred a thousand years later, when Nightmare Moon escaped from her prison. Learning that the elements had been left within the sister’s old castle within the Everfree forest, Twilight Sparkle, Applejack, Rainbow Dash, Rarity, Fluttershy and Pinkie Pie set off to find them. Eventually they found them, and their newfound friendship allowed Twilight to activate the elements and bind their power to the six of them, this enabling the six to break Nightmare Moon’s armour and make her Luna once more.
After this the elements were taken back to Canterlot and sealed in Celestia’s Palace. However the transfer of the elements from Celestia to Twilight Sparkle and her friends weakened Discord and allowed his to escape, Celestia calling the group back and opening the room containing the elements. However they were missing, apparently taken by Discord.
Eventually they were found in a hollow book in Twilight’s library, but by then the group had been corrupted by Discord to the point that they couldn’t use them anymore. Eventually Twilight managed to rediscover the spirit of friendship however, and use it to heal the others as well. Re energised they confronted Discord and used the elements to seal him once again, hopefully for good this time.
AppearanceIn depictions of the elements during their use by Luna and Celestia they take the appearance of golden balls, set with different coloured crystals. They bear the same general appearance when found by the main characters in Friendship Is Magic Part 2, though at this point both the balls and the crystals they contain have turned to grey stone. Nightmare Moon even manages to break them in this form, but upon Twilight’s realisation of her friendship with the girls shards of the broken elements fly back towards them and transform into a set of five necklaces set with crystals bearing their cutie marks, and crown bearing Twilight’s. Given this it can be assumed that they change form depending on who they are attuned to, though no explanation is given for why they turned to stone.
Power and UseThe elements, though extremely powerful, appear have rules to their use. These are muddied slightly by their off-screen use by the sisters, as their defeat of Discord has them sharing the elements between them and Celestia appears to command them single handily to banish her sister. Suggestions that events have been simplified over time and they really had friends bearing the other elements, that this is a product of their unique race or situation, or that the elements functioned differently in the past are speculation for now, though all are possibilities.
Use of the Elements by the six main characters however relies on them all being present, Twilight’s recruiting of Spike to fill Rainbow Dash’s position didn’t produce any magical effect at all. It also relies on them still representing their elements, Discord’s corruption rendering them powerless.
According to Celestia, she cannot use the elements anymore. Whether this is due to them being transferred to the main characters or earlier factors is still uncertain. Apparently, transferring the elements from one person to another weakens the persistent spells created with the elements. The main characters inheriting the elements from Celestia rendered Discord’s stone prison weak enough for him to use the fighting of the Cutie Mark Crusaders to draw enough strength to break free, something that Celestia hadn’t anticipated.
The exact effects of the Elements are uncertain. They have only ever been seen or referenced being used offensively against the most evil and supernatural of villains, and it’s uncertain what their effect would be on more common foes. On the two individuals they have been used on they produced three separate effects. Both times they were used on Discord they turned him to stone. Against Nightmare Moon the first attempt by Celestia banished her to the moon, and the second attempt by Twilight Sparkle and her friends cleansed her of the magic she used to become Nightmare Moon.