[Guido]

Ever felt walking into a narrow maze and blindly following the trail with no room to collect your thoughts in order to make sense of your surroundings? And, that's when you failed to notice the encroaching darkness has already consumed and left you helpless but to wait for the impending outcome.

When I first came across the manga I felt sullen, bitter, and powerless reading page after page at how the new recruits were begging for their very existence as they rode with Erwin to their very deaths.

It was such a powerful imagery, and now that I got the chance to watch it adapted into the anime medium my heart sank into the bowels of my gut; almost felt like crying.
Over and over the Beast Titan kept relentlessly pitching his game until getting what was left of Erwin's regiment, literally, stuck on the wall without a possible way out for the Scouts to survive.

This is when another powerful scene later came into the play and was Erwin privately confiding to Levi the futility of never reaching the basement, in spite of the mountain of corpses he built in order to get them this far.
From my interpretation, this crucial exchange made Levi to come to terms that Erwin was always a flawed person just like him and the rest of humanity.
It is precisely why they have to make the most of their deaths and their dread in order to pin down the trail that would eventually lead them to decisive victory, and that's why it was imperative for Erwin to step into the battlefield to lead those frightened recruits right into their deaths as there was no one else left capable of such task.

Deftinitely, the episode closing down with that shot of Erwin getting mauled by the boulders paints a fatalistic cliffhanger for what's to become of the Scouts the next episode, but with only death a certainty nothing else in life is either guaranteed or secured. Henceforth, now that Erwin and the Scouts accomplished their mission with their deaths, then I can only hope that this will suffice for Levi to accomplish his at the other end.
If all comes falling down according to Erwin's last strategy, then sooner or later the Beast Titan might pay a terrible price for his hubris.