During the battle to take Liones, Derieri and Monspeet notice a strange disturbance and go to see what it is. When they arrive, they find a giant pig causing havoc, being ridden by some unusual travelers. Originally curious at Elizabeth Liones's resemblance to a person she once knew, Derieri later became enraged when Elizabeth uses Ark on her and attempts to kill her only to be blindsided and seriously wounded by Meliodas. She falls off the pig and Monspeet rushes to her side.
Once Derieri regains consciousness, she spends a significant amount of effort to heal her wound with her darkness. Getting over the initial shock of seeing Meliodas alive, she devises a plan to kill him again. She tells Monspeet that she will distract Meliodas, and when the opportunity presents itself, he should hit both of them with his strongest attack. Monspeet at first feigns ignorance of what she means, but she assures him that she will survive the attack as she believes that she is much tougher than Meliodas.
She then charges off and Monspeet summons many lesser demons to help Derieri build up her Combo Star ability. After hitting 51 demons, Hawk Mama and Hawk, Meliodas blindsides her again by pile driving her into the ground thus resetting her combo. Enraged, she begins attacking Meliodas again, screaming at the traitor, but he easily parries all of her blows until attack number 12, in which he resets her combo once again by dodging her punch and hitting her from behind.
Monspeet gets into position in the sky above the fight. Meanwhile as Meliodas continues to parry her blows, he admits that "If I can help it, I'd rather not kill you guys." As Monspeet unleashes his Kaijinryu, Meliodas continues that his previous statement is something the old him would have said and proceeds to kick Derieri into the sky. He then activates his Black Mark and uses Full Counter with a sinister smile on his face, telling her to die. Monspeet rushes into the fray to save her and they are both consumed by the rebound.