Real World Example : Movie Critic

The original
from Burr,Ty. A darker 'Knight' July 2008

These are good and necessary things to ponder, yet they're nearly lost in the cross-cutting clutter. You come away impressed, oppressed, provoked, and beaten down, holding on to Ledger's squirrelly incandescence as a beacon in the darkness.

Parallelism appears in critics a lot, especially in Movie critics. Their purpose is to give the readers a brief but attractive information to the movie.
In this sentence,"You come away impressed, oppressed, provoked, and beaten down, holding on to Ledger's squirrelly incandescence as a beacon in the darkness.", The first three adjective is talking about the experience of the viewer of the movie. The later phrases are trying to even stronger the idea of how impress the view will be.

In stead of the original witting, this is a alternative:
These are good and necessary things to ponder, yet they're nearly lost in the cross-cutting clutter. You come away impressed, oppressed, provoked and even more, beaten down, holding on, to Ledger's squirrelly incandescence as a beacon in the darkness.

The commas will helps to strength the words"down" and "on" in order to describ the exciting experience in the film.