Signer Dragon

The Five Dragons are a series of Dragon-Type Synchro Monsters, introduced in Yu-Gi-Oh! 5D's. These legendary dragons play a part in the legend of the Crimson Dragon, as well as being connected to the Signers themselves. That connection being that these legendary beasts who are actually servants to the Crimson Dragon, were the ones who sealed an evilness within the Nazca Lines.

That same evil, which is now known as the Earthbound Gods, has reappeared once again in the world as Duel Monsters cards used by the Dark Signers.

So far 4 of the Five Dragons have been released in the OCG and TCG: "Stardust Dragon", "Red Dragon Archfiend", "Black Rose Dragon" and "Ancient Fairy Dragon". The supposed mechanical version of the fifth dragon, Power Tool Dragon, was released in Raging Battle.

In the anime, Professor Fudo gave the "Stardust Dragon", "Red Dragon Archfiend" and "Black Rose Dragon" Duel Monsters cards to Rex Goodwin. As these three, along with the "Ancient Fairy Dragon" card were originally designed so that their corresponding Signer could activate the safety switches for the Old Enerdy system.

Each of the revealed four dragons has at least one special support card for themself except Ancient Fairy Dragon.

Members
The Signers possess the card forms of the Dragons. Currently no Signer has been shown to use the fifth Dragon, which has no not yet appeared as a card in the anime.

"Power Tool Dragon", which belongs to Leo, looks like a mechanized version of the fifth Dragon, resulting in Leo believing he is the fifth Signer. Luna tells him it's possible that Power Tool Dragon fought alongside the Five Dragons in the ancient war between the Dragons and the Earthbound Immortals, but she only does so as not to sadden him, as a mechanical dragon could not have existed in ancient times.

Assault Modes
"Stardust Dragon" and "Red Dragon Archfiend" have their own "/Assault Modes": "Red Dragon Archfiend/Assault Mode" and "Stardust Dragon/Assault Mode". Both of them were Summoned by Yusei and Jack in a special episode.

Example:



Savior Modes
The Savior Dragons are upgraded forms of the Five Dragons, similar to the /Assault Mode monsters, summoned by Tuning Salvation Dragon - Savior Dragon with one of the Five Dragons and 1 non-Tuner Monster. They tend to have multiple powerful effects, currently being the strongest of all Synchro Monsters, but are balanced out by returning themselves to the Extra Deck during the End Phase while reviving their previous form from the Graveyard.

So far, only 2 have been revealed: Savior Star Dragon and Savior Demon Dragon, which were both used in the anime by Yusei Fudo and Jack Atlas, respectively.

Example: