The dakini also symbolizes the final, most advanced stage of enlightenment on the Vajrayana path.
The first stage is the guru, who initiates the student. The second stage is the “devata” stage, when the student follows a devata’s example in practicing meditation.
As mentioned, the yidam also enters into the process of Tantri meditation. The yidam is sometimes called a “meditational deity,” since it helps one meditate.