The Dragon's Flame (also known as Dragon Fire and Sacred Fire) is the source of Bloom's magic and also the Winx's source of power during the sixth season (due to the Legendarium stripping them of their magic).
In Season 2, the Winx finds out that there is a force that has the opposite power of Bloom's flame. Instead of giving life, the Shadow Phoenix, which can take form of both a man or a phoenix, has the ability of absorbing magic and life.
In Season 3, to defeat the man whose abilities are rooted from the Dragon Fire's darkness, the Winx travels to the Golden Kingdom and earns the Water Stars by going through the Crystal Labyrinth. These are ancient powers that is said to be the only force to extinguish the Dragon Fire. They also learn that to keep the fire burning, wizards sent the stars away to another realm.
In Season 4, not much is seen about the Dragon's Flame, but it is shown from Bloom's spells that it has the ability to heal and strengthen one's soul.
In Season 5, it can be concluded that in a certain realm called Infinite Ocean, there are pillars that sustain all the given life from the Dragon. When disturbed, it can cause chaos on Magix, or worse, the fall of the entire dimension. And also, her dragon fire seemed to be as powerful as it is both above ground and under the ocean.
In Season 6, Bloom splits her flame and shares it with her comrades. Soon, they find out that she weakens slowly after she shared it. With the fire of the Vortex of Flames in Domino, Bloom's supply of fire energy is replenished. In the late season, they soon find out that her flame is not that powerful enough to melt the Snow Queen's enchanted ice magic.
There are two parts of the Dragon's Flame which were shown in the series: a purer fire that Bloom possesses and a darker fire that belongs to Valtor, which was the result of a spark from the Dragon's fiery breath falling in and mixing with the Darkness (possibly part of the Shadow Phoenix's power, since both the Dragon and the Phoenix are supposed to have been born together from the Void at the Beginning of Time and it is probable that Valtor's Dragon's Flame was the result of the mixing of these powers). The power of Lord Darkar (The Phoenix) is the polar opposite to the Dragon's Flame since, while the Dragon releases energy through the Magic Dimension, the Phoenix's power absorbs that very energy.
According to the original RAI version, the Dragon's Flame has been passed down through generations of members of the royal family of Domino since the disappearance of the Great Dragon, and was used by the Nine Nymphs of Magix, nine all-powerful fairies who controlled the Fate of the Magic Dimension, the last and most powerful Nymph being Daphne, and the present Guardian being the Winx.
When Bloom was still a baby, Lord Darkar tried to obtain the Ultimate power and for that sent the Ancestral Witches to claim the Dragon's Flame from its Guardian to use it to obtain the Ultimate power. The Ancestral Witches and their "son" Valtor destroyed Domino in the process, but ended by being defeated by the Company of Light when King Oritel and Queen Marion of Domino imprisoned Valtor in the Omega Dimension and the Ancestral Witches in their own birthplace, the Realm of Obsidian in the final battle opposing the two sides. King Oritel however was grabbed by the Ancestresses, Queen Marion entered the King's Sword to stay with her husband and a wave of Dark Energy was released from Obsidian which caused all the inhabitants of Domino to also become trapped in Obsidian.
Princess Daphne managed to save her little sister Bloom and the Dragon's Flame from falling into the hands of Evil Forces by sending her to Earth, the cost of it being that she was herself turned into a bodiless spirit by the witches and is now a ghost bound to the Lake Roccaluce, where she is able to leave only temporarily.
For fifteen years (Bloom was apparently one year old when Domino was destroyed), the whole Magic Dimension thought that the Dragon's Flame had been extinguished in Domino's destruction, except the Trix (the descendants of the Ancestral Witches) who, using the power of the Vacuums, felt that the Dragon's Flame was out there, still burning and went after Stella's ring since it had been created, like the Sword of Oritel, using the Dragon's Flame.
Bloom, who had lived on Earth thinking she was a normal girl, first manifested her powers by saving Stella and went to Alfea. There, by observing Bloom's magical abilities, her interest for the history of the Dragon's Flame and the attempts made by Daphne to contact her sister, Faragonda realized that Bloom was the last heir to the Kingdom of Domino whom everyone had thought dead and the Guardian of the Dragon's Flame, which was thought to have been forever lost. Trix also realised that Bloom wields the power of Dragon's Flame after she released huge bursts of energy in episode 9 and 10.
This fact was openly revealed to everyone when the Trix, who had taken over their Ancestors' quest for the Dragon's Flame revealed this to Bloom after they seemingly stole it from her (when Bloom regained her powers Daphne told her that she had never lost the Dragon's Flame, but only began to have doubts about her existence, which caused her to be unable to use her powers, implying that the Trix never really had the Dragon's Flame, but since they thought it was in them they were able to use their magic as if they were its new Guardians) and Bloom openly used the Dragon's Flame in the last battle against the Trix at Alfea.
In the second season, Darkar tried to obtain the Ultimate Power of the Realm of Relix, and he turned Bloom evil when he realized that his power of Darkness was still ineffective in opening the portal to Relix, and that he needed a power which was his power's opposite to counterbalance his powers and that this power was the Dragon's Flame. However, when he was on the point of gaining the Ultimate Power, Sky admitted to Bloom that he loved her and Bloom healed herself from the evil spell Darkar had cast on her to make her evil, and helping destroy the Shadow Phoenix with the help of the Winx.
How exactly the Phoenix was destroyed was not shown, except that the Winx used a Charmix Convergence, but it can be speculated that when they did the convergence together with Bloom, they summoned positive energy generated by the Great Dragon which itself when it met the negative energy embodied by the Phoenix caused the two forces to annihilate each other, though it does not explain how the Dragon's Flame continued to exist while the Darkness of the Phoenix was destroyed. It's possible that some power of Dragon's Flame (as well as powers of overs) was consumed in a process of destroying Darkar. That explains the fact that Winx did not used their Charmix powers in season 3 but only their basic transformation and Enchantix instead.
Another possibility is that, since the Dragon's essence creates energy, it has unlimited strength, but the Phoenix has limited strength as its power is derived from all the energy it absorbed. However on the official Winx Club website it was said that Darkar's power was equal to that of the Great Dragon itself, implying that the Dragon's Flame cannot destroy the Phoenix of Shadow without itself being destroyed.
However, it could be that the Charmix convergence only destroyed Darkar's body and that his power still survived. In the first episode of the season, Wizgiz told the Alfea students that every power needs its opposite to balance itself, like the "yin and yang" concept in Chinese philosophy. This would mean that to maintain balance in the Magic Dimension, the Phoenix's power maybe still exists in a disembodied form just like the Dragon's Flame continued existing in a disembodied form even after the Great Dragon itself had disappeared.
In the third season, Miss Faragonda tells Bloom that when the Great Dragon created the Universe, a spark of it fell into the Darkness and mixed with it, becoming a Dark Dragon's Flame which remained in the Void for a very long time, until the Ancestresses found that Flame and fashioned it into a man called Valtor, whom they raised as if he were their own son and sent him, once he was old enough, to conquer all the Dimensions.
However, when Domino was destroyed, Bloom's birth parents defeated Valtor and trapped him into the Omega Dimension when they thought that everything they had, including their daughters, were dead (they had apparently not seen Daphne saving Bloom and being cursed by the Ancestresses or maybe Valtor lied to them by saying he had killed their daughters since they sealed him in the Omega Dimension for having killed their daughters) during the final battle of the Company of Light.
Valtor was awaken again when the Trix, who had been captured from Relix, were sent to the Omega Dimension and freed him. Valtor allied with the Trix and escaped from the Omega Dimension, wreaking havoc in the whole Magic Dimension when he did all he could to steal all the magical treasures of the Magic Dimension to become the supreme sorcerer of the Universe and tried to take revenge from the members of the Company of Light, despite doing his best to avoid fighting Bloom since she also had the Dragon's Flame.
For that sake, Bloom forced herself to gain her Enchantix, being unable to gain it normally by saving someone from her own realm even though it was an incomplete Enchantix, and the Winx went to the Golden Kingdom to find the Water Stars which contained the power which naturally opposed the Dragon's Flame so as to use them to extinguish Valtor's essence. However, Valtor even captured the Water Stars shortly before losing all his stolen spells which returned to their respective Realms of origin. During the final fight with Valtor, Bloom (her Dragon's Flame essense) got inside of Valtor's body and used her Fairy Dust to extinguish his part of the Dragon's Flame from within and destroyed him forever, therefore destroying the part of the Dragon's Flame which had mixed with the Darkness.
In the fourth season, the Dragon's Flame is no longer the source of the series' thread, the season being focused mainly on the Believix powers and the Earth Fairies' history. It is seen that that the Dragon's Flame was useless against Ogron, even at Enchantix level, as he only absorbed the power of the attack directed against him.
In the Believix powers, the Dragon's powers manifests itself as Bloom's Strength of Life power which she uses to heal the hearts of people and causes them to become better people and open their hearts to magic, as a result of the Dragon's Flame being the Flame of Life and of Good which created all the life in the Magic Dimension, and its ability to heal people.
This also manifests itself in the Sophix transformation, where Bloom's Sophix power is the Inner Flame, which is the power to reach each creature's soul, to never give up and to be born again. However, the Dragon's Flame seems weaker in the season since the power of Believix depends only on people's faith in magic and their ability to open their hearts to goodness and magic, which is maybe why Bloom's Believix attacks seemed much weaker than those in normal, Charmix and Enchantix forms.
In the Lovix transformation, the Dragon's Flame manifests itself in the form of the Ice Flame, and gives Bloom the ability to use ice-based spells. The Major Fairy Aurora, who has an ice power powerful enough to freeze the whole Universe, also sensed a very powerful power of fire in Bloom, and said that she did not want a Fire and Ice battle against Bloom.
Bloom shares parts of the energy of the Dragon's Flame with the Winx, as a result the Winx all obtain a new transformation called, Bloomix, that has the Dragon's Flame as the source of its power. When she gain Mythix, it is unknown if her powers are still strong but she was able to use her spell even without her wand.
During first movie, when Bloom's hope of finding her parents are revived by Daphne, this new spark of hope causes a Flame in the Sword of Oritel to start burning again.
The heat released from the Flame in the Sword is so intense that it causes horrible pain to the Ancestresses, and they ask their server, Mandragora, to find where the Dragon's Flame is and destroy it. For that, Mandragora goes to Domino, where she feels the presence of a fairy having the power of the Dragon's Flame in her and infects Riven with an evil bug which stings him, causing him to become a mere puppet in her hands.
When she attacks Alfea and is defeated, Faragonda calls Bloom by her name after the latter uses her Dragon's Flame to capture the witch. Mandragora, sealed again by Faragonda in Obsidian, reveals to the Ancestresses that the Guardian of the Dragon's Flame is a fairy called Bloom.
The Ancestresses wait for the Winx to come to Obsidian, where they try to force Bloom to destroy the Sword of Oritel. Bloom refused, saying that if she destroyed the sword it would also destroy her powers, perhaps because the Sword contained a piece of the Dragon's Flame or because her mother might have been another or a previous guardian of the flame.
In the end Sky ran the sword through Mandragora, who was possessed by the three witches' spirits, while Bloom attacked her using the Dragon's Flame, killing Mandragora, destroying the Realm of Obsidian, restoring Domino and all its inhabitants (including Oritel and Marion) to their proper states, and accidentally freeing the Ancient Witches.
The Dragon's Flame is seen when Bloom attacks one of her suitors because of his bad manners and his insolence. It appears again when the Winx fight the Trix and the Ancestresses at Havram.
Bloom then summons the power of the Great Dragon to face Icy, who was possessed by Belladona. Icy also used a Dark/Ice Dragon against Bloom, but both were of equal power. Finally, the Winx use a Believix convergence to summon all the essence of the Great Dragon and destroy the Ancestral Witches forever.
When the magical pollen of the Tree of Life which was released by the sprig of the Tree at Havram returned their ability to use magic to the Winx, Bloom was then able to use the power of the Dragon's Flame, being its Guardian, to attack Icy.
It is possible that the Winx were able to summon the whole power of the Dragon with their Believix by believing in their full powers as the Fairy Guardians of the Magic Dimension, and by believing that they could make Good triumph over Evil and defeat the Three Ancient Witches (it is to note that in the Magic Dimension the Great Dragon has always been the symbol of Good against Evil, possibly symbolized by Darkar, as stated by Tecna in season 1) plus the powers of Bloom as Fairy of the Dragon's Flame and the positive magic from the Tree of life which was being released from the sprig (the powers of the Dragon being positive ones, opposed to the negative powers of the Phoenix).
The Dragon's Flame is primarily a beneficial magic power giving Bloom the ability to break very powerful spells and heal people. In the RAI version of The Crypt of the Codex, she is even able to heal Sky, who was dying. In the 4kids version, Sky was just under a deep sleep but Bloom still brought him back.
Her healing powers develop in season four when Bloom develops the spell Strength of Life. She healed extremely weak people, such as Mr. Baston, Mike in the fire, Roxy after she was possessed by Nebula, and people in station in Gardenia.
The Dragon's Flame manifests itself in the form of dragons or balls of fire. While Bloom mainly uses her powers to bombard her opponents with fireballs in varying intensity and size, she soon learns to ignite large wildfires and control dangerous infernos by thought. Other related abilities are throwing blasts of heat energy, using fire as shields and force fields, causing objects to become soft and melt, shooting beams of orange energy and using fire to fly.
- Healing: The Dragon's Flame can heal the wounded, the dying and those who have been put under evil spells (including Bloom herself), but strangely Bloom did not use it to heal Nabu when he went into a coma while she was in her Believix form (probably because it does not work on dead persons).
- Activating the Water Stars: Only a possessor of the Power of the Dragon's Flame defeat can activate the Water Stars; this can be extremely dangerous, as mentioned when Bloom said she would need the Stars to defeat Valtor because they possess the only power which can extinguish the Dragon's Flame and can destroy all the powers of the Keeper of the Dragon's Flame using them.
- Senses: Bloom can pick up on others emotions and intentions. It can look people aura. When Bloom received her Bloomix she gained the ability to sense other magical objects.
Bloom's regular offensive and defensive spells as well are based mostly on the fire, i.e. Fire Arrow, Dragon Fury, etc. Most of them are flame-colored, with added accents of bright cyan, and, in Lovix, purple.
- The Great Dragon and the power of the Dragon's Flame were probably inspired from the Phoenix Force of the Marvel Comics which is described as one of the oldest known cosmic entities, representing life that has not yet been born. The Phoenix Force is an immortal, indestructible, and mutable manifestation of the prime universal force of life. Born of the void between states of being, the Phoenix Force is a child of the universe.
- After Bloom earns Sirenix, the Dragon's Flame appears to be less effective underwater, although its power is supposed to be limitless. In other way, Aisha's Morphix powers seems to be more powerful.
- Even though the Dragon's Flame is the life force of the Magic Dimension, Bloom is never shown to give life to other things, unlike Flora who has shown the ability to give life to plants and stuffed animals.
- Despite the fact that Bloomix transformation is powered by Dragon's Flame, no one from Winx (except Bloom of course) uses flame based atacks. Instead everyone uses their own array of defensive and offensive spells. It can be explain due to fact that Dragon's flame is origin of all powers and can morph itself in different powers depending on owner choice (which explains why Trix were able to use it in their spells in season 1, despite the fact that they used it for an evil purpose)