“The Man of Stone” (1932)
Read in 2018.
Clunky, particularly in the slow development of the plot over months, and the language is never striking. Unusually for Lovecraft, the mechanics of the wizard’s magic are relatively clear (the Book of Eibon has chemical recipes to be combined with blood sacrifice), and the protagonist who reads his diary is not personally pulled into a climactic scene. The twist is thankfully feminist, though it constitutes a “final girl”.
References here: “Out of the Aeons” (1933).