Browsing through the Beinecke Library alchemy works collection I was struck by similarities between two pages of Ars Notoria (Mellon MS 1 here) and the Voynich manuscript f86r.
Ars Notoria contains prayers mixed with magic words (mostly made-up names). The book was not favored by the church, but was present in the inventory of Canterbury, Charles VI of France, the Dukes of Milan and was heavily researched in Bohemia by Mattheus Beran at the very beginning of the 15th century ( here).
Beinecke Library also owns a fine copy of the Ripley Scroll (Mellon MS 41 here) were we find alchemy process illustrated by eight circles pointing to ninth one in the center, which reminds of the 'nine rosette' VMS f86v. Similar 9-circles configuration is also found in 17th century alchemy book woodcut (Beinecke, Z92 15 here).
Similarities of the Voynich manuscript with alchemy works seems to be bad news for researchers (especially when magic words are involved).