While giving his enthusiastic blessing, Lovecraft also provided Bloch with a bit of Latin to use as an invocation from the book: "Tibi, magnum Innominandum, signa stellarum nigrarum et bufoniformis Sadoquae sigillum"—which can be translated as "To you, the great Not-to-Be-Named, signs of the black stars, and the seal of the toad-shaped Tsathoggua".
In "The Shambler from the Stars", De Vermis Mysteriis is described as the work of Ludvig Prinn, an "alchemist, necromancer, [and] reputed mage" who "boasted of having attained a miraculous age" before being burned at the stake in Brussels during the height of the witch trials (in the late 15th or early 16th centuries).
The book plays a larger role in "Black Bargain" (1942), in which it is described as "Philtre Tip" (1961), quite literally a shaggy dog story, cites "Ludvig Prinn's Grimoire, in the English edition", as the source for the recipe for a love potion.
It appears in "The Haunter of the Dark" (written as a sequel to Bloch's "The Shambler from the Stars") as a "hellish" book found with other forbidden texts in the Starry Wisdom Church in Providence, Rhode Island.
In a 1936 letter to fellow Mythos writer Henry Kuttner, Lovecraft mentioned De Vermis Mysteriis as one of the books that "repeat the most hellish secrets learnt by early man".