These are traditionally known as the "four activities" and are actually fairly advanced bits of tantric practice. Usually one engages in these activities only after the completion of a given approximation and accomplishment, at least according to Kagyu lineage. In Nyingma, you''ll find rituals relating to these practices at the end of Drupchens. Most often, they take the form of "Fire Pujas"--"Jinsek" in Tibetan, or "Homa" in Sanskrit...activity rituals that serve to enact the given activity. Most often, especially for beginners, one engages in "pacifying" activity.
"Negative Projections" would be a way of discussing obstructors, particular to Trungpa's approach, I think, or of obstructions in environment and sentient beings, in general.
The Four activities, or "Lay Shi," as they're known, are: Pacifying, Increasing, Magnetizing, and Destroying. Increasing can be called "Enriching," and is concerned with growth, and also with things like spreading the Dharma, causing the Dharma to flourish. Magnetizing can be called "Attracting," and is traditionally used to magnetize good qualities to oneself, including life force, wisdom, etc. Also useful for gathering students. Destroying is sometimes called "wrathful."
Some yidam practices focus on one or another of these activities, even prior to engaging in the actual "post-accomplishment activity." Other yidam practices are manifold, and address more than one of the four activities. For example, Kurukulle is a magnetizing practice, as is Vajrayogini to some degree. Green Tara is often said to be an "enriching" practice. Chenrezig is the king of Pacification deities, in all his forms. Mahakala, and Vajrakilaya, Etc., are known by their "destroying activities" attributes, primarily. Hevajra, Chakrasamvara, are more multivalent, it is said.
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