Dark Queen

The Dark Queen (黄泉の女王), also called the Queen of the Underworld, is the final boss of Sonic and the Black Knight. It is a transformation of Merlina the Wizard, achieved through the power of scabbard of Excalibur. Merlina assumed this form when she tried to make her kingdom everlasting by applying the scabbard of Excalibur's immortality-granting magic to the world of Camelot, but she was stopped by Excalibur Sonic and Excalibur before she could destroy the world.

Appearance
In her standard form as the Dark Queen, Merlina appears as a darker version of her regular self. Her long red-violet hair has turned violet-blue and hangs lose and voluminous behind her back with a large and detailed red hairclip adorning it. Her skin has also turned white, her eyes have turned amber yellow, and below her left eye, she has gained a tattoo composed of two curved violet-blue lines.

In terms of attire in her standard Dark Queen form, Merlina's cloak has become black, with the hemlines having turned orange, the symbols adorning it having turned yellow, the lock on her chest having turned red, and has gained large white feather-like extension on the rims. Likewise, her dress has become black, with the symbols adorning it having become purple and her belt having become red, with white feather-like extensions adorning it as well.

In battle as the Dark Queen, Merlina can assume the appearance of a giant ghostly version of King Arthur. This spectral form of King Arthur, while sharing many of his characteristics, is colored completely black with an aura of blue flames, is equipped with an eye on its chest, has four arms, whereas two of the arms are connected at the hips, no legs and a cloth-like tail. On the back of this form, Merlina has dozens of cape-like energy strips floating, and a large circle composed of medieval symbols at the top of her back. In her two lowers arms she has two copies of Deathcalibur, and in her two upper arms she has two short orb-like wands.

History
The Dark Queen is essentially Merlina after she betrayed Sonic. With the scabbard of Excalibur, Merlina called upon the forces of the underworld to spread the scabbard's immortality-granting magic to the entire kingdom, and she assumed her true form the Dark Queen in the process. Using her High Ancient Magic, the Dark Queen created the Dark Hollow and began enveloping the kingdom in the underworld's forces.

Eventually, the Dark Queen was confronted by Sonic and Caliburn in the Dark Hollow. As Sonic questioned her actions, the Dark Queen calmly replied that the kingdom would end one way or another and began to solemnly tell about its grim future. Not willing to let this future come to pass despite her grandfather's efforts, the Dark Queen desired to make the kingdom eternal with the scabbard, but Sonic refused a world without an end and attacked her.

The Dark Queen easily repelled Sonic, before deciding to kill him with her shadow, cleaving and seemingly destroyed Caliburn in the process. Despite beating Sonic to an inch of his life, the hedgehog continued to attack her in vain. Suddenly, however, Sonic received the remaining Sacred Swords from the Knights of the Round Table, transforming him and Caliburn into Excalibur Sonic and Excalibur. In response, the Dark Queen transformed into a giant ghostly version of King Arthur and confronted the duo. Eventually, however, the she was worn down and was dealt the final blow. With her defeat, the Dark Queen reverted back to a normal Merlina, who was then redeemed when Sonic convinced her to live her life to the fullest in their time they had.

Powers and abilities
As the Dark Queen, Merlina's High Ancient Magic have been vastly increased and she can control the forces of the underworld to further argument her strength and influence. In this state, she is so powerful that she can beat back opponents like Sonic the Hedgehog, who at the time possessed Caliburn and had advanced swordsmanship skills in addition to his normal abilities, without any effort.

The Dark Queen possesses impressive senses and reflexes, being able to keep track of Sonic's movements and react according to them.

With her magic, the Dark Queen is capable of conjuring up impenetrable barriers that can repel enemies with extreme force, levitation and teleporting objects. She is also able to call forth a physical manifestation of her own shadow in the shape of King Arthur that she can control at will, which has enough physical strength to cleave through Caliburn's blade and heavily injuring Sonic, and has fast enough movements to strike even Sonic.

Due to possessing the scabbard of Excalibur, the Dark Queen can as well bestow immortality to anything she desires, making the object in question immortal and everlasting.

The Dark Queen can also transform herself into a gigantic spectral and demonic version of King Arthur. In this form, the Dark Queen possesses enough strength to fight on par with Excalibur Sonic, and has enough physical durability to withstand several sword slashes from Excalibur, the greatest of all sacred swords. She can also, in this form, call upon her magic to form temporarily barriers to protect herself, though they can be broken by Excalibur Sonic's attacks, and project energy balls. She has also demonstrated efficient swordsmanship in this form, being able to dual-wield two large Deathcalibur-like swords at once and use them effectively in combat.

Boss guide
At the beginning of the battle, the Dark Queen will summon an invisible wall which can only be broken through if Excalibur Sonic deals enough blows to it or enough energy balls are launched. Once the wall is broken, the Dark Queen starts firing multiple energy balls in strings which can either be dodged right by pressing or left by pressing. Alternatively, the player can deflect them with attacks. Once the Dark Queen's energy ball onslaught is finished, she will attack Excalibur Sonic in the same way King Arthur attacks Sonic with his sword. Likewise, Excalibur Sonic must block each blow by swinging the Wii Remote at the right time. When launching one attack however, the Dark Queen may do an unexpected sword trust with her other arm. Excalibur Sonic must counter her sword strikes multiple times to fill the Soul Gauge in order to attack with Excalibur Sonic's Soul Surge. After dealing enough damage, the Dark Queen will turn black and inflamed, which will make her attacks more random. After dealing enough damage to her from this point, a small in-game cutscene will appear and the battle will be over.

By attacking the Dark Queen at the right time during the Soul Surge will replenish the Soul Gauge slightly, thus extending the duration of Excalibur Sonic's Soul Surge and shortening the length of the battle.

Quotes

 * "This kingdom will fail one way or another. Such as its fate."
 * "Lancelot and Gawain's rift shall doom the Round Table. Arthur is struck down by his son Mordred and departs for Avalon."
 * "This was to be our ideal world, but it will not last. 'King Arthur and the Knights of the Round Table will end in ruin."
 * "The King Arthur my grandfather Merlin created led to nothing but mistakes, but I can succeed with the power of the scabbard, creating a kingdom that never ends."
 * "My sorrow at its ruin runs deeper than the depths of the Underworld. Do you not understand?"
 * "Your efforts are futile."
 * "It is time to end this."
 * "You would not understand, nor could you understand. That's why I must do what I must do. I am finished with you."
 * "This story and the world it created will come to an end. Is that what you wish?"
 * "Your blade can not touch me."
 * "I thought the sacred sword Excalibur was a mere legend."
 * "Why can you not understand how magnificent an everlasting kingdom will be?"
 * "You could never understand my sorrow at seeing the ruinous future of this kingdom."
 * "Your selfishness is going to be the end of it all."
 * "Aaaaaaaaah! But I.....I....! Aaaaaaaaah!!!" - When defeated by Sonic

Trivia

 * The battle resembles the final duel with Alf Layla wa-Layla in Sonic and the Secret Rings since both are played in a different dimension and both introduce a new transformation for Sonic (Darkspine Sonic in Sonic and the Secret Rings and Excalibur Sonic in Sonic and the Black Knight).
 * The Dark Queen's spectral form looks very similar to King Arthur.
 * She even uses his sword, Deathcalibur.
 * The Dark Queen is the only villain who doesn't wish to destroy or rule over everything. In fact, her goal is the opposite, since she wants the story's world to last forever.
 * She is the first female antagonist and final boss that Sonic has fought.
 * There is a way to defeat the Dark Queen in very little time. As perfect hits are dealt, the soul gauge will keep filling, up to a point where a second will fill on top of the first. If the second gauge gets maxed out, the player will win automatically.
 * If the player defeats her with five Mastery Stars, the player will obtain a profile of Merlina.
 * When telling Sonic her intention to make the kingdom that last forever, she summons a yellow carnation. A yellow carnation means disappointment or dejection. This implies her disappointment with either:
 * Sonic not approving of her desire.
 * Her sorrow to her world ending.
 * Refusing to let her world end.
 * The image of the Dark Queen at the beginning of her boss fight is actually a texture, not a 3D model.
 * Her transformation does not include her actual name like most transformations.