D&D 5E: Adventure: Fifth Edition Fantasy #32: The Lost Vault of Tsathzar Rho

A simple expedition to get rid of a marauding ogre soon becomes more than it seems. A mysterious force has transformed the ogre and the kobold tribe he once bullied into twisted, demented creatures. When the characters enter the ogre's cave, they find a passage behind leading deep into the mountains. Soon they arrive at the lost vault of the sorcerer Tsathzar Rho, where they are confronted with the terrifying dangers of a lost epoch!