We don't have synonyms for octalogy yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are ontology, otology and datalogy.
(n) :
(rare) A set of eight works of art that are connected, and that can be seen either as a single work or as eight individual works. They are commonly found in literature, film, or video games.
(n) :
(rare) A set of eight works of art that are connected, and that can be seen either as a single work or as eight individual works. They are commonly found in literature, film, or video games.