 Lady of The Lake.
King Alined came to Camelot, seemingly wanting to create a peace treaty with King Uther and the "five kingdoms". However, what he really wanted was war. Alined's jester Trickler put a spell on Arthur to make him fall madly in love with King Olaf's daughter Vivian. When Olaf found out about their relationship, he became furious and challenged the Prince to a duel. Arthur eventually won, but spared Olaf, saying that this wasn't the way to make peace. King Alined left Camelot, angry at his failure to stir up trouble.
During this time, many other sorcerers who had been wronged by Uther over the years joined Alvarr's cause, the most famous of them being the Druid boy Mordred.
Alvarr later became determined to obtain the Crystal of Neahtid, a magical item that can show the future to those who can use it. Knowing that Uther's ward Morgana had a connection to Mordred, Alvarr approached her and used both his charisma and Mordred to win her over. Morgana stole the Crystal of Neahtid and delivered it to the camp, and Mordred was pleased to see her. Back in Camelot, Merlin visited the Great Dragon and he was told of an ancient prophecy foretelling an evil alliance between Mordred and Morgana. When Arthur, Merlin and the soldiers attacked the camp, all were killed apart Alvarr, who was captured and taken back to Camelot to be executed while Mordred managed to escape from the knights of Camelot. Uther tried Alvarr for treason and sentenced him to death, but he would not get the chance to see this. Morgana, who had now officially turned against her guardian, drugged all the guards watching Alvarr, allowing him to escape.
Morgause later awoke the Knights of Medhir to kill Uther. She also approached Morgana, and got her on her side. She then placed a spell upon Morgana, binding her life to a sleeping spell that she placed on Camelot. The spell put everyone in Camelot to sleep, with the exception of Morgana, Arthur and Merlin (who were away when she cast the spell). Merlin, after visiting The Great Dragon, learned of how to stop the Knights, and reluctantly poisoned Morgana with hemlock. Morgause, upon hearing her sister's telepathic screams, confronted Merlin and demanded he tell her what he used to poison her sister so she could heal her. Merlin refused to do so unless she killed the Knights. Morgause chose her sister over her chance to kill Uther, and used her magic to kill the knights. Merlin showed her the hemlock, but Arthur and the Knights of Camelot soon burst into the room. Surrounded, Morgause used her magic to take Morgana away from Camelot and saved her life. The sisters were united to start planning the attack of Camelot.
After taking a sword from a Knight Medhir an artifact of the Old Religion, Merlin returns to the Great Dragon. He asks what the Dragon's intentions are once released, but the Dragon cryptically replies that there is only one road he can take. Merlin asks the Dragon to promise to not harm Camelot, but the Dragon simply replies that he believes enough bargains have been made. Merlin wields the sword and frees the Dragon who roars in triumph and escapes to freedom ready to attack Camelot.
Arthur was later forced, along with his knights to defend Camelot from The Great Dragon who was freed by Merlin (though Arthur didn't know it) and attacked Camelot every night as revenge for his imprisonment and the near extinction of his kind. After realizing that the Dragon was too powerful for them to defeat, Arthur and Merlin went on a mission to find Balinor, a Dragonlord and (unknown to Arthur) Merlin's father. They found Balinor who at first refused to return to Camelot, believing that it was perfectly fair that The Great Dragon should have revenge for everything Uther had done to him. Balinor was eventually convinced to return when he realized that Gaius, whom he owed a life debt, was in danger. Arthur told him he would be rewarded but Balinor replied that he sought no reward. Unfortunately the Dragonlord was fatally injured by an enemy king's knights and died in Merlin's arms.
Arthur and Merlin arrived back at Camelot and reported the death of the last Dragonlord. Then they went out with Arthur's knights to make one last attempt to kill The Great Dragon. The Dragon presumably killed all of Arthur's knights but Arthur rolled under a stream of fire and managed to land a blow on the Dragon with his sword. The Dragon retaliated by smashing him with one of its huge front legs, knocking him unconscious. Merlin, who had gained the powers of a Dragonlord thanks to his father, banished the Dragon from Camelot.
Uther spent almost a year sending soldiers to look Morgana refusing to give up no matter how many knights were lost. He declared he would never give up searching despite being told by Gaius that, after an entire year, he should call off the search and accept that Morgana was gone. However, she was eventually found one day alone in the woods by Merlin, Arthur and his men and returned to Camelot.
Morgana finally returned to Camelot after being taken away by Morgause. Unknown to all but Merlin, she had turned to evil and was bent on destroying Camelot. The sisters attempted to conquer Camelot with the help of King Cenred while Uther was incapacitated by a strange illness, but their plans were foiled by Merlin.
Merlin released a Goblin.
Merlin and Arthur meet Gwaine.
The deceased man Taliesin appeared to Merlin and showed him the Crystal Cave.
Arthur's marriage to Princess Elena was arranged, but cancelled at the last minute by the mutual consent of the young couple.
Gwen and her brother Elyan were kidnapped by Cenred. Arthur, Merlin, and Morgana(reluctantly) later rescue them.
Arthur went on a quest to find the Golden Trident.
Morgana plotted against Arthur again when he went on a quest to find the golden trident and she tried to kill him by using a Phoenix Eye in a bracelet. However this failed because Merlin removed the Eye from Arthur's arm and gave it to the Fisher King, foiling her plan.
Gaius reunited with his old lover Alice.
Arthur and Gwen's relationship was threatened by Uther, who sentenced Gwen to death. Merlin disguised himself as Dragoon the Great and confessed to planting the poultice (which was actually planted by Morgana) under Arthur's bed. Gwen was later released.
Merlin met another sorcerer called Gilli who wanted to achieve glory in the annual tournament but also kill Uther for having his father executed when he was young. Merlin, having been told by Kilgharrah that Uther's death would turn Arthur against magic, protected Uther from Gilli and later convinced him not kill Uther.
Morgana and Morgause eventually managed to get their hands on the Cup of Life. Using this to turn Cenred's army immortal, Morgause overran Camelot's army and captured the castle. Morgana and Morgause overthrew Uther and Morgana was crowned Queen of Camelot. This event also marked the death of King Cenred who was later killed by Morgause.
Merlin used the water from the Lake of Avalon that the Fisher King gave to him to contact his former lover, Freya. She told him to meet her at the lake, where she will hand him the sword he threw in earlier, with that he has the power to save Albion. When Merlin sent for Lancelot to aid Arthur after Morgana's conquest of Camelot, Percival he volunteered and accompanied Lancelot.
Fleeing from Morgana's immortal army in Camelot, Arthur led a group of outlaws, consisting of Merlin, Gaius, Guinevere, Elyan, Lancelot, Percival, Gwaine and Leon, to the Castle of the Ancient Kings. The group uncovered the Round Table. Arthur along with Merlin managed to save Camelot from Morgana's rule. Merlin managed to destroy the immortal army, allowing Arthur to rescue Uther while Morgana was forced to escape with Morgause who was defeated by Merlin.
Merlin used his magic to fuse Excalibur into a large stone.
Another year later, Morgana attempted to take revenge on Camelot took the wounded Morgause to the Isle of the Blessed. After Morgana sacrificed Morgause at the Isle of the Blessed, in order to tear the Veil between her world and the Spirit world, she released the Cailleach. The Cailleach then warned Morgana of Emrys, allegedly Morgana's destiny and doom, not telling her that he was in fact Merlin. Arthur learned that the only way to defeat the Dorocha is to make a sacrifice. Before Arthur can sacrifice himself, Merlin sacrificed himself and was apparently killed.
Merlin was cured by Vilia and traveled to the Isle of the Blessed with Arthur and the knights. Lancelot sacrificed himself to to defeat the Dorocha and prevent Arthur and Merlin from sacrificing themselves.
Odin sent an assassin, the Gleeman to assass