The Sunken Library of Qezzit Qire (2019)

From the introduction:

Qezzit Qire, an elf scholar who valued his privacy, built a library in the marshes south of modern-day Tolmezo. His library was the subject of considerable derision—it stood in the shadow of the Great Library of Friula, and the damp location seemed antithetical to maintaining books. The elf had the means to acquire books, sometimes in opposition to the Great Library. When Qezzit sniped books destined for the Great Library, it enraged the library’s head administrator, who schemed to end the rival library’s existence. Rumors about forbidden and vile tomes sequestered in the elf’s library spread quickly. The reclusive elf never refuted the rumors, and, eventually, an armed mob marched toward the library to burn it down. As word of the approaching mob reached the library, the patrons fled, leaving just the elf and his staff. Faced with the threat of losing everything he had procured and despairing at the impact to his studies, Qezzit performed a ritual to consign himself and the librarians into undeath and sink the library. The elf then crafted an illusion of an explosion within the library and its subsequent sinking, which coincided with the mob’s arrival.