So I've been seeing a lot of people claiming the Azath is a Deus Ex Machina (DEM).

I disagree, here is why:

For at least half the book it appears that the finnest is the McGuffin (McG) for Lorn and Tool.

So, can something be both McG and a DEM?

Here's the common definition for both:

* In fiction, a MacGuffin (sometimes McGuffin) is an object, device, or event that is necessary to the plot and the motivation of the characters, but insignificant, unimportant, or irrelevant in itself.

*A DEM is a plot device whereby a seemingly unsolvable problem in a story is suddenly or abruptly resolved by an unexpected and unlikely occurrence.

In the face of these I'd posit that:

1) If a seeming McG serves in an active way in the articulation of a plot point, it then ceases to be a McG, as it's no longer "insignificant, unimportant, or irrelevant in itself".

2) If a seeming DEM is expected, likely, or part of a solution thought up in advance by characters, then it ceases to be " a seemingly unsolvable problem in a story [that] is suddenly or abruptly resolved by an unexpected and unlikely occurrence".

Taking this into account, it would appear that the finnest is neither, as it is crucial in solving the endgame problem in an active and somewhat expected and likely way.

However doubt would still remain as the finnest "birthing" an Azath is not explicitly stated as being an expected result of its presence at the Fete; and therein lies the rub:

Are the "expectation" and "likelyhood" of events in the description the reader's or the characters'? In books like MBOTF does the distinction need to be made? Can the distinction be made?

In a book where the narrator and povs are intrinsically unreliable and/or limited (and in general, where most information is intentionally obscured), can we convincingly make the case either way?

I'm not certain it can, but further reading almost always get readers to a place of definite trust in SE's storytelling abilities, so does it even matter?

For what it's worth my vote goes to "not DEM", what's your take?