There is no dark side of Tantra. Conscious work is always conscious. Unconscious work is always unconscious. To work within deeper Tantric elements is to just invite simple conscious death. It is simple in its intimate ordinariness. It is conscious in its pure light. It is death, for it is death.
The Dark Side of Tantra is the true side of all that is impossible.
There is Lightning. There is Thunder. There are Rains. There are Showers. There is the Calm and there is the Storm. There is a Rainbow. There is a True Covenant. There is a True Blood.
Within the deep resting, all is well.