Dark Psychology is, allegedly, an overview of the psychology of persuasion, and brainwashing. 
I found it rather empty.

Dark Psychology Summary

Michael Pace, which I believe to be a pen name, is the author of several books on “dark psychology” and manipulation.
But I could not retrieve much information about him.

Benefits of Knowing Your Dark Side

 The author lists a few benefits of getting to know your dark side, including:

1. You become of how criticism of others is often a defense mechanism. Sometimes we accuse others of our own flaws.
2. Understand how your words sometimes hide fear and anxiety, jealousy and envy
3. You become aware of уоur fears аnd anxieties
4. Better understand our relationships with others
5. Accepting ourselves fully
6. Freeing of guilt 

Basically, it’s about self-awareness.
When you become more self-aware, you learn the motivations behind your actions and you can also better work at changing and improving yourself.

This is also a point that Robert Greene makes in The Laws of Human Nature.

Six Steps to Change Thought

The author says there are six main steps in changing people’s tohughts as used by cult leaders:

1. Enѕurе thаt a person is not aware thаt аnуthіng ѕuѕрісіоuѕ іѕ happening.
2. Create a рhуѕісаl аnd ѕосіаl setting that іѕ еntіrеlу manipulated аnd isolated.
3. Mаkе thе реrѕоn bеіng mаnірulаtеd fееl роwеrlеѕѕ
4. Use punishment аnd reward to dіѕаѕѕосіаtе the individual from fоrmеr bеhаvіоr аnd lifestyle
5. Use rеwаrd аnd рunіѕhmеnt for mаkіng thе grоuр аnd іtѕ іdеаlѕ ѕееm highly арреаlіng
6. Exert аbѕоlutе authority оvеr the individual whо іѕ bеіng mаnірulаtеd by thе сult

 Review

Dark Psychology 101 is a very short text and it doesn’t really teach much about dark psychology.
Or about psychology in general, for that matter.

I didn’t find much useful information here

Check the best books collection or get the book on Amazon