In Vajrayana there appears to be many different types and stages of mediation. One form is called "completion stage meditation" also known as nispannakrama. It appears to be associated with something called Anuttarayoga Tantra. What exactly is "completion stage meditation" and how is it practiced?
According to what I understood from explanations given to me in one of the temples in New Kadampa Tradition, completion meditation is an antidote to potential sideeffects of generation meditation. If practitioner gets too attached to (image of oneself as) one's yidam, they are prescribed certain exercises designed to help them let go.