Lessons with the Black Wizard

Lessons with the Black Wizard is an event that takes place during the Tenrou Jade arc.

Prologue
After their shameful defeat against Blue Skull, Mavis, Yuri, Precht, Warrod and Zera flee to the forest outside Magnolia and tend to their wounds. As they recover, Mavis offers to fetch water, blaming herself for their own failure. When she arrives at the lake, a young man appears from beneath the water and asks her to promptly leave the forest; after exiting the water and declaring that he will leave the forest instead, a mysterious black wave emanates from his body, killing the surrounding wildlife. Zeref proceeds to explain that anything that comes near him dies, an anomaly which Mavis recognizes to be the work of Ankhseram Black Magic, her recognition of his condition shocking him. Making claim that his curse is why he avoids contact with humans, animals or otherwise, Zeref explains that, after being asked if he gets lonely, the very fact that he was able to have a normal conversation brings him joy. He turns around to leave (not wishing to accidentally kill Mavis), only to be stopped by a group of wild animals surrounding him; at first taken aback by the appearance of the animals, after Mavis explains that they are illusions and that Zeref can touch them, he tries to do so and thanks her for her gift. After that, sensing that he is an amazing Mage, Mavis asks the man to teach her and her friends Magic, which he agrees to do.

Magic Lessons
Later in the night, the group is gathered round the fire, meditating, much to Yuri's annoyance. The man then starts explaining that Magic comes for the Ethernano particles that exist in the air, in which the Mages absorb into their body, stating that the absorbed amount differs from one user to another, despite it being a renewable energy. The wizard then reveals that what is more important than transforming a one's Magic Power is actually the strength of his feelings and emotions, which affects the control over Magic. The man then leaves, claiming that they will continue in the morning. The following day, the group continues their practicing, with Precht being the first to succeed in absorbing the Ethernano, in which the man compliments him. In the evening, Yuri continues to meditate but in vain, he then jumps and starts exercising, stating that it's how he set his heart free. This is proven right as the Treasure Hunter starts absorbing the particles and goes to brag about it to his comrades.

Precht manages to employee his Magic, being able to fire bullets from his hand. Meanwhile, Mavis finds some difficulty in absorbing the particles, while Zera manages to unlock her Fire Magic, as the Dark Mage watches them. However, Warrod fails to conquer his Magic in his physical practice, while Yuri keeps training under a waterfall, stating that it won't be called "training" if it's without it. Out of the blue, the Treasure Hunter is struke by a lightning bolt coming from the sky, much to his surprise. Eventually, all of the group advances in its Magic techniques, except for Mavis and Warrod. Later at the camp, Yuri and Precht discuss their new Magic and ask about their comrade's, in which he replies that is fine. He then leaves to search for sticks, with Mavis following him. Warrod starts bemoaning about his lack of strength and holding back his comrades, in which Mavis comments that they have just said the opposite, as they owe him a lot for saving them many times and that it's their turn to protect him, much to the latter's delight. He then goes to meet the Mage teacher, asking him to teach him a Magic in which he can support his friends with. The Mage then stats that there is a Magic suitable for the "color of his soul".

The group wakes up to the sight of a great tree rising up, in which they recognize as Warrod's new Magic. Later on, Mavis is talking with Zera about her being the only one left, just for the Black Wizard to appear before them. The hunters are enthusiastic by their new power, claiming that they're ready to fight. All of sudden, Mavis appears in a dark maid outfit, addressing herself as the Black Wizard Mavis. They then wonder about the mysterious Mage's whereabouts as none of them have seen him. The wizard is then shown walking away, calling his time with Mavis a "treasure".

Aftermath
After their lessons with the anonymous Mage, The group sets a plan to invade Magnolia and ignite a revolution against Blue Skull. Eventually, Warrod and Mavis manage to trap Geoffrey, Blue Skull's Master while Yuri and Precht were attacking the guild's base at Kardia Cathedral and retrieving the Tenrou Jade. Unfortunately, the Jade is revealed to contain tremendous Dark Magic and shouldn't be touched physically. This is proven right again, as Yuri is transformed to a skeleton dragon upon holding the Jade.