The Search-and-Destroy Force「掃討部隊 Sōtō Butai」 are a division of the allied forces of Stigma, the Holy Knights and the Seven Deadly Sins formed during the new Holy War, designed to confront the Demon Clan's army and clear the way to Camelot
Before the imminent Holy War against the demons, Merlin took care to divide the allied forces to face them. The "Search-and-Destroy Force" was designated as the largest group of the three representing the military force that would directly confront the army of the Demon Clan and would open the way to Camelot to the south. The group is formed by many of the Holy Knights of Liones under the command of Howzer, along with Sariel and Tarmiel as representatives of the Four Archangels, and Diane, King and Gowther as representatives of the Seven Deadly Sins. Gilthunder was to lead the Holy Knights with Howzer, but then decided to go to Camelot with the "Assault Force".
Before that, Ludociel used his Breath of Bless to empower most of the Holy Knights including the Pleiades of the Azure Sky in the group, so they may stand a chance against the Demons despite the psychological effects on their minds as zealots.
During the advance to Camelot, the group is confronted with the demon army. Initially, the Holy Knights are oppressed by numerical superiority and resources and are forced to retreat. However, Diane and King manage to eliminate much of the enemy army by themselves using their new abilities, while Sariel and Tarmiel easily do the same with an Omega Ark. The princess Elizabeth Liones took the path of diplomacy and managed to convince many of the demons to retreat and abandon the battle.
In the end, the group manages to defeat the entire enemy without any loss, thanks to Elizabeth's efforts to heal and keep everyone alive.
While trying to regroup, the group is surprised by the presence of Derieri of the Ten Commandments, who was persecuted by Estarossa, who wanted to kill her and steal her Commandment. The forces are attacked by the Black Hound of Estarossa, but are saved by Diane. Estarossa is sent back by Elizabeth and engages in a battle against Sariel and Tarmiel.
Initially, Sariel and Tarmiel have the upper hand grant to their Graces, until Estarossa absorbed the Commandments of Truth and Reticence that he has recollected, obtained such power that he was able to surpass the two Archangels, but his mind comes more unstable. Guila, Diane and King tries to fight him, but with no effect and Guila ends seriously wounded. At the end, Elizabeth sacrifices herself and allow to be taken by Estarossa. Upon regaining their original bodies, Sariel and Tarmiel go to rescue Elizabeth and kill Estarossa. King and Derieri decides to join them while the rest continues the way to Camelot. Hawk and Gowther also go after Elizabeth without the rest noticing.
The four of them arrive at the Heaven's Theater and see Estarossa's violent reaction due to taking in three of the Commandments but their memories of Mael and Estarossa are soon warped as they begin to notice the inconsistencies and soon the forbidden spell that Gowther placed on everyone 3,000 years ago begins to fall apart and "Estarossa" is revealed to have never existed and was in fact Mael this entire time who was turned into a Demon after the Demon King was tricked into giving him the Love Commandment.
There, a battle is unleashed between Mael and King, who tries to protect Gowther from being destroyed. Sariel, Tarmiel and then Derieri join him, but Derieri ends up being killed and her Commandment absorbed. While Mael unleashes a terrible energy absorbing a fourth Commandment, the bodies of Sariel and Tarmiel end up destroyed.
After feeling what happened, Diane is separated from the Search-and-Destroy Force and with the help of Oslo, go to Heaven's Theater to help in the battle. Although the Sins and Elizabeth give everything to fight against Mael, the power of the Commandments ends up being very big, with Oslo having to sacrifice his life and the Theater being completely destroyed. However, King manages to fully develop his wings, gaining his true power as Fairy King, overpowering Mael completely. The Archangel begins to have a breakdown because of the Commandments ripping apart his mind and body, but Gowther manages to use his Invasion to enter his mind and save him by convincing him to expel the Commandments from his body.
The rest of the Search and Destroy Force meets with the Fairy and Giant Clan armies led by Matrona and Gerheade, who join them on their way to Camelot. The group soon faces a second wave of demons, unleashing another hard battle. In the middle of it, Elaine exhaust all her magic power and reach the end of her life a second time. However, Ban appears in the last moment and sacrifices his immortality to bring her back.