From publisher blurb:
Some of the greatest and most feared figures in the history of the multiverse earned their reputations or positions by mastering the secrets of magic. From the crazed wizard who built three high towers and sealed demon lords in the dungeons below them, to the accursed mage who descended into the Abyss to confront the Queen of Dragons, to the chosen mage of the Goddess of Magic, whose influence has helped shape entire realms, these figures command power unmatched by other mortals. Magic makes of them gods when compared to the mundane peoples. And although many such beings have earned esteem for their good works and heroic exploits, others have surrendered to their base desires and used their superhuman magical abilities for selfish ends.
The Blasphemies of Bor Bwalsch, a supplement for 5th Edition, reveals a selection of twenty-four spells created by one of the multiverse’s most sinister figures. As his native realm was being swallowed in the shadow of some cosmic destroyer, he used his magic to breach the boundary between realities—and through the fissure he fled, bringing his dreadful advances in dark magic to the unsuspecting world he now calls home.