Seven Sages of Destruction

Introduction
The Seven Sages of Destruction were a group of seven powerful demon mages who served the Demon King until his demise. They seemed to work under the Demon King's confidant, the Omniscient Schlacht. In the past, the Sages were important generals of the Demon King Army, securing key areas of interest in the Northern Countries. In a battle against all of the Sages and Schlacht, Three of the Seven Sages were taken down by the Hero of the South. Two Sages, one of which was the Immortal Bose, were defeated by the Hero Party. After the Demon King was defeated by the Hero Party, the remaining Sages of Destruction either went into hiding or disappeared. Twenty-eight years after Himmel's passing, Aura the Guillotine was defeated by Frieren. The last remaining sage is Macht of El Dorado.

Immortal Böse
Little is known about Bose other than the fact that he was vanquished by Himmel and his Party. His eradication became one of the adventure tales of the Hero Party.

Bose was seen briefly in the flashback of Chapter 62 along with all the other Sages of Destruction. He wore a helmet and had horns growing to the sides instead of growing upwards like other demons.

Miraculous Grausam
Other than the brief appearance in Chapter 62, Grausam made an appearance in Chapter 98 in Macht's memories, where his appearance was used to threaten Macht to comply with Schlacht's demand. Not much is known about his magic aside from the fact that he is the worst match for Macht.