Poison is Medicine
The Core Texts of the Heart Essence of the Vast Expanse consist mostly (though not exclusively) of texts belonging to the three inner tantras of the Mahāyoga, Anuyoga and Atiyoga. These contain practices that can only succesfully be completed under the guidance of a qualified tantric teacher.
Recently, Dzongsar Khyentse Rinpoche has published a new book, Poison is Medicine, written in response to the misunderstandings and misapprehensions about the Vajrayana that were exposed by the Vajrayana guru-related scandals of the 2010s. He says:
One of my reasons for writing this book is that I would like us all to think about and examine the various issues the recent Vajrayana guru scandals have brought to light, from as many different angles as possible.
My wish is to offer aspiring Vajrayana students a few tips from the tantric texts about how to choose their guru. This book will, I hope, point you in the right direction by supplying you with the tools you need to examine a guru thoroughly before committing yourself.
Adam Pearcey, an advisor of the Longchen Nyingtik Project, has written the foreword to the book.
The book is freely available on the website of the Khyentse Foundation.