The manifestation of creatures that feed on peak experiences.
An example of creatures that feed on pain, trauma and sudden death may be what some have seen in the World Trade Center smoke.
See the part of a letter that explains this.
Warning: People who join in groups that share peak experiences (i.e. sex and/or drugs, etc.) and do not concentrate on manifesting something usually end up creating a vacuum that needs to be fed (all the participant(s) is thinking is "more"). May be better for such groups if they were to put a trusted person in charge of reminding them to concentrate on effecting the astral/physical in some way during the peak experience.