The world of Black Clover is a fascinating one where mana and magic stand as a fundamental part of society as they are used for everything ranging from day-to-day activities to epic battles against terrorists and evildoers. The mana used by the mages gives them great power, but there is also a dark side to it.
Forbidden magic spells are those that utilize the dark mana of the underworld in its negative form. Even though there are serious consequences for using forbidden magic, many characters in the Black Clover series are willing to take the chance in order to gain the upper hand against more formidable opponents.
7 Secre
Secre Swallowtail was initially portrayed as the anti-magic bird Nero, who was often found at Asta’s side. However, as the Black Clover series progressed, Nero was revealed to be Secre, the servant of the first Wizard King. She was born into a noble family that deemed her sealing magic useless. However, at the first Wizard King’s side, Secre found what only she could do with her sealing magic.
Zagred, the demon, arrived during the reign of the first Wizard King. He used his influence over the demonized former elf leader, Licht. After Licht was defeated and Zagred's plans were thwarted, Secre used black magic to seal Zagred.
6 Licht
As the leader of the elves during the first Wizard King’s time, Licht was a powerful and noble elf. He befriended the original Wizard King, Lemiel Clover. After the elf tribe was slaughtered, however, Licht lost faith in Lemiel. Eventually, Licht learned that the demon Zagred was to blame; Zagred had driven Licht mad in order to steal his powerful body and grimoire.
After apologizing to Lemiel Clover for doubting him, Licht employed prohibited magic to transform himself into an all-powerful demon in order to prevent Zagred from taking over his body. Asta uses the five-leaf grimoire that was once Licht's after he became a demon.
5 Patolli
The strong elf Patolli posed as the terrorist Licht and led the Eye of the Midnight Sun, a group of rogue wizards who sought to destroy the Clover Kingdom. Under the guise of Licht, all Patolli wanted was payback. He harbored a grudge against the people of Clover Kingdom for the centuries-old killing of the elf people.
Patolli cast the forbidden magic spell Evil Eye, reincarnating the souls of dead elves into human bodies using human hosts, in order to destroy the Clover Kingdom. The host's soul is sent to sleep when the spell is cast, and while they're unconscious, their normally dark and muddled thoughts become even more so.
4 Zagred
Zagred is a powerful devil who treats the lives of humans and elves as if they were toys to be played with whenever he pleases like the devil. Zagred takes great pleasure in wreaking havoc wherever he goes. He planned the first Wizard King's elven genocide and inspired Licht to create his five-leaf grimoire.
When Licht and Lemiel Clover foiled his schemes, Secre locked Zagred away for all eternity. Unfortunately, the devil utilized black magic to reincarnate himself hundreds of years in the future, allowing him to escape prison and use his future body to create chaos.
3 Vetto
Vetto is an ancient elf who was filled with despair and hatred towards humans when he witnessed the massacre of the elf tribe centuries ago. Centuries after the elf tribe’s massacre, Vetto was reincarnated into a human body by Patolli. His feelings of hatred towards humans were further enhanced due to the side effects of reincarnation magic.
Like Patolli, Vetto used forbidden magic. His reincarnated self was itself a product of forbidden magic; furthermore, he opened the evil third eye when he encountered the magic knights of Clover Kingdom. After using the evil third eye, Vetto became immensely stronger, with a sinister aura around him. Vetto raged like a wild animal until the Black Bull magic knights intervened.
2 Fana
Like Vetto, Fana is one of the ten apostles of Sephirah and serves as the third eye of the Eye of the Midnight Sun terrorist group. Like many other elves, Fana hated the humans of Clover Kingdom due to the first prince’s 'betrayal'. After being reincarnated with forbidden magic, Fana’s feelings of hate and prejudice towards humans grew even more.
Fana was a good person who agreed with Lemiel and Licht that all races should be treated equally. After her rebirth, however, she hardened her character and became more cruel and violent. Fana was so concerned about her fellow elves that she would risk her life to get revenge while under the influence of prohibited magic.
1 Megicula
As one of the highest-ranking devils of the underworld, Megicula possesses immense power. She is extremely sadistic and intelligent, using humans as playthings to satisfy her curiosity. When bored with humans or her underlings, she kills them without a second thought, showing how whimsical she can be. As Megicula shares the same form of depravity with her current human host, Vanica Zogratis, the duo gets along well.
Among Megicula’s many talents is her ability to use forbidden magic despite the backlash that comes from such spells. Although forbidden magic often takes a toll on the user with a corresponding backlash, Megicula uses such spells with frightening ease.