As he said in this interview, Alexander Von Meilenwald sung the clean vocals on "I Raised This Stone As A Ghastly Memorial" in ten layered tracks.
The spoken excerpt in "Blood Vaults (I - Thy Virginal Malodour)", from the album Rain Upon The Impure, is taken from a poem in Edgar Allan Poe's The Fall Of The House Of Usher. The excerpt says:

"And travelers now within that valley,
Through the red-litten windows see,
Vast forms that move fantastically,
To a discordant melody."
"Beverast" is von Meilenwald's own derivation of the word "Bifröst" influenced by the Old High German term for the bridge between Midgard and Asgard.