The term "non-duality" oft appears in Buddhist English language literature, both contemporary and in translation. e.g. it is sometimes claimed to be the cornerstone of Yogacara philosophy, and its assertion of "mind only", that no part of us exists independently of consciousness, but nevertheless it does tend to have some existence.
Obviously the term nirvana means buddhist liberation, that point at which the sage or saint (both words appear in the English language literature) has put out the suffering of samsaric existence, be that its elimination or a realisation that it is, in someway, already so extinct.
Mara is the personification of skillessness, a character that deceives e.g. the aspirant away from the holy life, and as such represents (in a sentient being) let's suppose something like the opposite of skillful means.
I thought that nonduality often (if not always) means that opposing terms (good and evil, or illusion and reality) depend upon each other, by convention at least.
So, whether or not the last paragraph is correct, does the above not suggest that nirvana is mara?