Did you watch the attached video? It explains in great detail how local transient decreases of entropy are possible at the expense of increase of entropy elsewhere in the system. Thus, the overall entropy of the whole system, in fact, increases, and the 2nd law of thermodynamics is not violated. The video also nicely explains local transient formations such as stars and planets (and also your favorite -- black holes).

The same (non-violation of 2nd law of thermodynamics) can be also observed in the experiment (energy to information conversion) I mentioned in the linked article at the bottom, or in the experiment dealing with reversing entropy by sending Qubits "back" in time. (When the whole system is considered -- computers, all machines, cables, etc. -- 2nd law of thermodynamics still holds.)

So perhaps, it would be more accurate to talk about "illusion of violation of 2nd law of thermodynamics," as the decrease of entropy, indeed, does happen, albeit in a spatiotemporally limited way and always compensated for in other parts of the system. Again, for how this is possible, watch the video -- there's no anomaly to speak of.

Now finally for monism and the inherent problem with explaining "illusion." As I said in the second to last sentence, it all boils down to a limited perspective. Either spatiotemporal, and, in the case of living organisms, also perceptual.

Of course, these incomplete approximate views (or "illusions") do exists (are real). They just don't represent what's really going on. In perceptual realm they are like fata morgana (in spatiotemporal realm, e.g. the entropy discussed above, they are simply incomplete conclusions, ironically, also only perceptual -- Universe "knows" the whole picture). The "illusory" nature of perception can be demonstrated by deliberate alterations, and even complete shutdown, of perception itself.

That, however, is not a problem as such because our "human tailored" perceptual illusions are functional in terms of orientation, navigation, activity, etc. and the "human interface" will always perceive Universe through that lens (of itself).

However, "human interface" on top of all of that also allows for not only self-awareness (as many other animal interfaces do too), but, due to more complex pattern matching (i.e. symbolic thinking), allows "observer awareness". In other words, we (can) ask, "Who is 'I'?"

Thus, we are left with an observation that death of human, planets, stars, even heat death of the universe (or cessation of natural order altogether) do not extinguish existence as such on one hand, and on the other we must ask who knows that, the latter of which can be known by carefully discarding everything observed (obviously, as what is observed is not the observer).

Here we are already firmly in the "realm of monism" -- "I Am", Brahman as consciousness-existence-bliss or knowledge-reality-infinity, etc. And mind you, as far as I'm aware, only humans ponder "illusions." Thus, despite the awareness of illusory nature of our perception, human has also tools to see through that illusion, so to speak.

Was that what you were asking?