An argument, or point within an argument which revolves around completely altering the topic of argument and using (twisting) semantics (meanings of words) as a means to prove (force) a point which either was never disputed or is so off the wall (for example, Maths doesn't exist) that to argue it would be to slaughter logic on the spot.
Often relies on the lack of universal, metaphysical definitions for entirely human concepts to argue that either it does not exist at all or that we cannot discuss them without omniscience, or similar faeces.
To effectively execute a Michaelov ploy one must 'quickswitch' the argument right at the end back to the original argument to make it seem as if they had effectively defeated a point.
It is a logical fallacy because the point made by a user of the michaelov ploy has no sort of logic within it.
Bill: I think religion is a force for evil
Ben: I have an issue with that <michaelov ploy> Since the word think means to have a mind, and a mind is nothing without a universal definition of evil, how can we truly say that we even exist? Without existing we can't say religion is a force for evil </michaelov ploy>
Bill: Wait..... what?
---- A more extreme version ----
Matthias: I object to homosexuals because I feel it is unnatural.
Michaelov: Without a universal definition of 'object' then you cannot object since you do not know the true nature of a physical object whilst in the universal realm of the object itself. Gays for president!
Matthias: o. O