Tantra has been much misunderstood, particularly in the West. Tantra is about expansion of consciousness, & liberation of energy.
The liberation of energy starts with the blocked energy within our mind, body, & emotions being freed, then the energies of the more subtle realms start to reveal themselves as the more subtle aspects of our being become more manifest & leads to the awakening of our own Divine energy, the great kundalini. But this is not all: as we progress, we also become conduits for the cosmic energy. All of this is a process & it all takes time.
With the expansion of consciousness, we start by simply becoming more aware, &, as we progress, the hidden powers of the mind manifest, & we eventually come to the Higher Consciousness that is inside each of us. Sometimes this is referred to as the 3rd eye. It is here that the true hidden personal power of tantra truly flowers.
Because tantra also involves the hidden world of the unseen, the unheard, the unknown, & the mysteries of the gods & goddesses. And, with tantra, we find ourselves aiming towards the gods & goddesses. Tantra is a process which leads us there. Tantra is also believed to mean "to weave". What is being weaved? The mysteries of our own psyche, the mysteries of this planet, the mysteries of the gods & goddesses, the mysteries of the cosmos. The dance of energy & consciousness on all levels.
Tantra is a process which recognises that we each have a starting point, & that we are also living a life; we are not living a reclusive life, we have a destiny in an incarnation which also must be fulfilled. And in this context, tantra does also include sexual practices. Unfortunately this has given tantra a bad connotation, as, both in the West & in India, the word tantra has been used unscrupulously in a sexual content. And so much misinformation has been "given out" regarding sex, in the name of tantra.
In the tantric texts are techniques to take us on our journey to the divine. Tantra also recognises that we need to have means to go on this journey: the techniques are to provide a vehicle. The techniques include ritual which also use the senses & aspects of nature, & invoking the gods & goddesses; sound (in India the sounds are called mantra); geometric symbols (yantra); circular patterns (mandala); intent, or, the power of the mind.
So, tantra is potentially very powerful. In India there are tantric sadhus (spiritual renunciates) who can & do transmit spiritual energy just by touch & mantra. There are also tantric shamans who perform rites to provide blessings, or to cast a spell. Some can cast a curse. The "bad" tantriks also use trapped beings to help them with their spells & curses, which is how so-called 'great' tantrics & gurus can manifest: it is by enslavement.
The world of duality, of consciousness & energy, day & night, darkness & light, good & bad, are all recognised as existing, in tantra. In reality, for the majority of us it is a joyous path, full of wonder & awe.