WARNING: The following contains spoilers for Season 5 of The Seven Deadly Sins, now streaming on Netflix.
Season 5 of The Seven Deadly Sins is chock-full of intense battles as the revived Holy War approaches its climax. Following Episode 4's reveal that Esterossa was truly the Archangel Mael, whose memory had been altered along with all who knew him by the Demon mage Gowther, Mael is consumed with rage. Still out of control after absorbing three Commandments, Mael elects to take revenge on Gowther, as well as his friends, the anime's fifth season, in the hopes of causing the doll as much pain as possible. But even for an archangel, the Commandments
In Episode 5, "The Tragic Strike," Sariel looks on as Mael battles King and Gowther, explaining to his fellow archangel, Tarmiel, that despite currently controlling the three Commandments he had previously absorbed, Mael's heart falls further into darkness each time he uses their power. As if on cue, two of Mael's four wings grow dark, and he begins to use both the powers of the goddess clan and those of the Demon clan.
To save Mael from falling into darkness, the two Archangels agree to help restrain Mael and remove the commandments. However, in the process, Mael is able to free himself and steals Derieri's Commandment, Purity. After taking in the Commandment, Mael is surrounded by a cocoon of light, which suddenly erupts with beams of darkness and light, creating mass destruction, even destroying Sariel and Tarmiel's physical forms.
When Mael emerges from the cocoon, he has six wings, half black and half white. In addition to his new wings, Mael's face is covered with a shroud adorned with the symbols of each of the commandments he possesses. This new form is a cruel twist on the classic shonen trope of a character gaining new power in a moment of need, most famously seen with Goku in Dragon Ball Z and his many Super Saiyan forms. However, Mael's new form isn't exactly a boon, as it basically turns him into a vengeance-fueled monster. Instead of seeking redemption from the fall Gowther forced him into, Mael reacted in anger, choosing to inflict more pain and suffering.
By Episode 6, "Confront Despair," Mael's power has grown to monstrous proportions. Now moving eerily as a silent specter, Mael coldly lashes out with his newfound strength. His new form allows Mael to use each of the four commandments he had absorbed, Love, Truth, Reticence and Purity, to create objects of immense power.
While this form grants Mael immense power, it comes at a high cost. Episode 7 reveals that Mael is actually hurting himself by taking this form. After awakening his full power, King can hear inside Mael's mind -- and what he finds is disturbing. Mael's mind seems to be torn in two as King can hear two versions of his voice, one crying out in pain and remorse over his actions as Esterossa, the other shouting threats. Clearly, the Commandments are tearing Mael apart mentally, despite his power as one of the four Archangels.
Thanks to his increase in power, King is able to hold off Mael long enough for Gowther to enter his mind. Once inside, Gowther finds him being slowly consumed by the Commandments, so lost in self-pity that he neglected to resist them, wondering why had Gowther chosen him to suffer.
Gowther explains that his creator, the demon mage of the same name, chose Mael because Mael had killed his lover. Upon this revelation, Mael ejects Gowther from his mind and, as the Commandments begin to consume him further, he comments that he reached the limit of his foolishness. Gowther falls back into the real world and King desperately races after him, but he is instead saved by Mael, who is no longer controlled by the Commandments.
Having accepted his fate, Mael begins to return to his former self, no longer consumed with the desire for revenge. This marks a turning point for Mael's character, as he begins to seek redemption by helping the Seven Deadly Sins in their fight against the Demon Clan.