When I teach a class in tantra yoga, people are always startled by the fact that tantra yoga has no rules. There is no asana. There is no sequence. The focus, you see, is on aware exploration of the body, not some sort of physical sequence that magically opens you up.
Most people in class are startled because their past hatha yoga classes have taught them that asana and sequences are kinda sacred. They are named after famous yogis and reputed to be handed down through millennia of practice. And if you do 108 of anything, you are sure to acquire karma points!
There is a physical and energetic opening that occurs during any conscientious hatha yoga practice, but that is because you are changing physical tensions as you move and moving energy around your body. But all too often, the high you get is the same high as running or bicycling or any other vigorous activity.