Reddit mentions of The Crystal and the Way of Light: Sutra, Tantra, and Dzogchen (Tibetan Buddhist Philosophy)

I, like many others, started out as what Chapman calls a Concensus Buddhist. Batchelor never really appealed to me, although I did used to adamantly deny reincarnation when I started all of this. Tantric Buddhism is Vajrayana, btw. David Chapman was (is still?) a practitioner of Nyingma Dzogchen. It's a really interesting school with quite a profound view that you won't find anywhere else. Their masters claim to achieve a "rainbow body" and can perform all kinds of spectacular wizardry like flying, producing emanations, etc. I'd recommend you dig further into it if Chapman piqued your interested. I'd recommend The Crystal and the Way of Light as a wonderful Dzogchen primer.

The Words of My Perfect Teacher is a great book on the preliminary practices in the Nyingma tradition. The preliminaries aren't much different from tradition to tradition, so it's pretty applicable regardless of the school. This book will give you a crystal clear idea of what your practice would be like for the first X,XXX hours of practice if you happen to begin a Vajrayana practice.

If you're keen on Dzogchen, you could also check out The Crystal and the Way of Light.

There is nothing else which is similar to "the ultimate" in Dzogchen except Mahamudra.

Unfortunately, it's really difficult to explain. Even the term "the ultimate" is misleading, so it was a bad choice of words on my part.

I remember when I first read about Dzogchen, I couldn't help but compare it to the Tree of Life, mostly the supernal triad and Ain, Ain Soph, and Ain Soph Aur, but also the whole notion of how phenomena came to be made so much sense to according to the YHVH formula and and the ray of creation, that I simply saw it in everything I read if something sounded similar. It seems to make so much sense, although in a vague and mysterious way, that it is easy to get stuck on, especially if you have used the YHVH formula to apparently manifest reality or perhaps "spoken" with the numinous in one way or another to confirm the validity of Qabalah. Once I had some experience with pathworking, it was difficult to shake the idea that Qabalah was not the absolute truth. What else could possibly manifest such perfectly verifiable experiences? But, I had trouble with the origins of the whole thing, since I am repulsed by the Bible and pretty much all forms of Judeo-Christian religions. It didn't satisfy me to think one was "exoteric" for the profane and one was "esoteric" for the enlightened, particularly because so many different schools had such different ideas about God, the gods, where the world was headed, what aeon we were in, what is "good" and "bad," etc. etc.

So, now that I've given some backstory on that, I will defer you to this link, which might make some sense to you, but frankly I doubt it... http://awakeningtoreality.blogspot.com/2009/10/dzogchen-rigpa-and-dependent.html

It is not something you can read about and understand, really. I learned that firsthand. The Western Mystery Tradition involves a lot of reading and thinking and I was just determined to try to understand Dzogchen intellectually for several years before I realized it just wasn't going to work... and then I finally started listening to all the Dzogchen teachers who had always said this. A little reading is okay, but practice is most important. And then, when you get some idea of what it's all about, reading may be more productive rather than just a complete waste of time trying to make sense of things that seem impenetrable.

I would also recommend some book for you if you're interested on a good introduction to Dzogchen:

The Crystal and the Way of Light

Dzogchen The Self-Perfected State

The Mirror

I recommend them in that order.

E: Also, this might be useful. It is 7 pages, notice the "next >" button at the bottom.
http://vajranatha.com/articles/dzogchen-and-meditation.html