The Kalachakra seed syllable (rnam bcu dbang ldan) or Tenfold Powerful One is the best-known symbols of the Kalachakra system, and probably of the entire Tibetan tantric tradition. The symbol consists of an ornamental ring of fire, then the main symbol which combines seven individual syllables, on top are a crescent, a disc, and a curved shape, making ten.
Surrounding the main symbol is a kind of frame made of flames, which corresponds to the outermost "Circle of Wisdom" of the mandala.
On the left and right of the actual Tenfold Powerful symbol are the Lantsa characters for E and VAM, representing the union of respective emptiness (E) and bliss (VAM).
