Aether/Nether
This information was mostly taken from a fandom powered Spyro Wiki, although there are both minor and major differences.
Aether(also spelled æther or ether and also called quintessence) surpasses all of the elements of the Realm. Its strength is equivalent of suns, gravity, and the righteous might of passing comets. It is the spiritual matter the very universe is made of, and the true element of The Purple Dragon. Fun fact, the purple dragon is just a nickname for a creature originally referred to as the Aether dragon. Aether's power resides within its connection to the cosmos and specifically to spirit energy. Magic left by the Ancestors in the form of Spirit Gems, allows for a window into this power on a spiritual level, as they stimulate the energy of dragons with a life covering essence obtained from spirit life force. Aether deals in matters that surpass those of the basic elements, and draws powerful magic from ancient celestial origins. It can be harnessed, and it is all about how the element uses energy, as it taps into the very soul of the Purple Dragon, and the spirits of others. In this way, energy can be transferred (as might be in the case of say, healing using the 'light' Aether) but other aspects of a dragon's energy can also be transferred.
In times of crisis, Aether would be the resulting breath a Purple Dragon would use. It has strong connections to the basic elements, and cosmic energy. Aether can be projected, repelled, altered, and even transferred, (as might be the case with a Purple Dragon lending its power or healing another by transferring its own energy). The more energy dealt with, the greater the toll may be for the Purple Dragon that dealt with it. A demonstration of this with light Aether would be if a purple dragon were to transfer their energy to someone with a curse. Transferring their positive energy to this person would reverse the negative energy of the curse, thusly breaking the curse and setting them free. However, transferring negative Aether to another would result in something known as a 'Nether curse'. While the purple dragon in question may not be transferring Nether energy to them, the result of transferring negative Aether energy would cause a reaction in the victim's body, resulting in the ability to harness Nether energy. The Nether curse also causes the target to submit to the will of the one who cursed them, as well as becoming a killing machine.
While Aether is responsible for cosmic and pure abilities, Nether is obtained through the dark side of the universal energy and replaced by the power between life and death. This element could be used as a means of connecting the spirits of darkness and life, and they command darker and more destructive abilities than Aether. While Nether is the most destructive element, it can still be used to for things such as reversing death. If Nether merges with a powerful spirit who possesses its polar opposite, Aether, the effects will corrupt and in turn possess them. While exposure to Nether infused Aether can cause permanent mental, physical, and spiritual side effects, some individuals can become immune to it. Those who are 'immune' to it, are still under its influence, however they are conscious and aware of what they are doing. Aether can also balance its opposite and retain minor de-corruption(that is, positive Aether can counter the effects of both negative Aether and Nether).
As the element focuses on mainly death-related properties, Nether resembles an atom smasher; which vaporizes its victims into nothingness. Its magic leaves behind destructive and withering effects. While Nether is seen as completely evil, it actually isn't. It's just really easy to become corrupted under its influence, but it can be harnessed without corruption. The only dragons, or beings for that matter, who are born with the ability to harness the power of Nether are night dragons. Night dragons are capable of controlling both Nether and the five uncommon elements.