This is combined with the yogas of highest yoga tantra deities such as GuhyasamÄ ja , Cakrasaá vara , YamÄ ntaka and KÄ lacakra , where the key focus is the direct experience of the union of bliss and emptiness . This is combined with the yogas of highest yoga tantra deities such as GuhyasamÄ ja , Cakrasaá vara , YamÄ ntaka and KÄ lacakra , where the key focus is the direct experience of the indivisible union of bliss and emptiness .