Lady of the Lake

Sonic and the Black Knight (2009)
In the world of book centered around King Arthur, the mighty King became a dark knight, taking advantage of creatures from the Underworld. He became utterly invulnerable through the power of the Excalibur Scabbard and wrecked havoc across the kingdom. Merlina, the granddaughter of Merlin, desperate to defeat the dark knight, summoned a creature from another world, which turned out to be Sonic the Hedgehog. Sonic faced Arthur in battle, but Merlina stopped the hedgehog and teleported him along with herself away from the battle. After explaining that Sonic himself could not defeat the King, the sorceress took the hedgehog to the place where the ancient sacred sword Caliburn rested in the stone. But alas, even the power of this sword was not enough to defeat Arthur and Sonic had to go on a journey to become stronger as a knight and defeat the dark king. Sonic finds a Blacksmith and sharpens Caliburn, then goes on a quest to find Lady of the Lake in order to figure out how to become a true knight. Along the way, Sonic is challenged by Sir Lancelot, one of the King’s loyal Knights of the Round Table, but Sonic defeats him and takes his sacred sword Arondight. Upon meeting Nimue, Lady of the Lake, Sonic is given three quests to prove his knightly honor – free the innocents from King Arthur’s dungeon, offer compassion to those in need and defeat King Arthur’s Knights of the Underworld. Sonic successfully passed all the trials also defeating Sir Gawain and taking his sacred swords Galatine, which led the Lady of the Lake to name him a true knight and revealed the weakness of Excaliburn Scabbard – invulnerability could be neutralized by three sacred swords used by the Knights of the Round Table, so Sonic defeats the last Knight – Sir Percival and takes her sacred sword Laevatein. 

After defeating all the Knights of the Round Table Sonic finally faces the Dark King and using the three sacred swords, Sonic disables the invulnerability granted by the Excalibur Scabbard and kills King Arthur, who strangely disappears in a haze like the creatures from Underworld. Sonic deliveres Excalibur Scabbard to Merlina, when suddenly, using the power of the Scabbard, Merlina begins to spread Underworld’s energy and send monsters into the area. Sonic and the Knights of the Round Table team up against Merlina and Lady of the Lake tells them how to build a barrier around Camelot using sacred swords, which the Knights do to stop the energy of the Underworld from spreading.  After putting up the barrier Sonic faced Merlina in battle but did not stand a few minutes against the power of the Dark Queen. In the end, Caliburn was broken and Sonic fell defeated. Lady of the Lake and the Knights of the Round Table watched the battle using a magic mirror. As Sonic was about to fall, the mirror suddenly glowed and Nimue shouted for the Knights to lower their sacred swords into it. Suddenly, three sacred swords materialized in the room where Sonic and Merlina fought and combined with Caliburn, the four swords formed the most powerful sword, Excalibur. Using Excalibur’s power, Sonic defeats Merlina, but doesn’t finish her off. Caliburn, being fixed after a transformation, shocks everyone by naming Sonic the true King Arthur.