Adalman/Chronology

The Octagram Soars Brightly Arc
During the war between Tempest and Demon Lord Clayman, Adalman battled against Shuna as the guardian of Jistav. She managed to hijack Adalman's Disintegration and purify the land, effectively freeing him and his fellow undead from the curse. Adalman admires Shuna's faith and wishes to serve the same God, pledging his alliance to Rimuru Tempest.

Majin Behind The Scenes Arc
Adalman was assigned to guard the 60th floor of Ramiris' Labyrinth, but was swiftly defeated by the Crusaders during their training run, due to him having lost most of his powers and the ability to use Holy Magic. Seeing this, Rimuru requested Shuna to study holy magic together with Adalman, as well as suggesting him to have Albert as his vanguard. Adalman also requested to summon his pet, which turned out to be an undead dragon.

Eve of War Arc
Adalman helped with the research and got along very well with the vampires and Luminous. As a reward and a token of apology, Luminous taught him the Day-Night Inversion, in which he improved into Holy-Demonic Inversion with the help of Beretta.

Bathing in the labyrinth's concentrated magicule, Adalman's party evolved into powerful monsters. They easily defeated Shinji, Mark, and Zhen even though they were high A Rank adventurers. After Rimuru learned of their improvement, he promoted them to the 70th floor.