I cannot say that this sort of thing happens often, at the very least I can say that I don't remember attending such events in the past, that's why I was somewhat concerned afterwards, not afraid, just wondering about the whole thing. I didn't feel threatened during the experience, however it was clear to me that the individuals present and the ritual being performed (which involved boars) had an infernal quality to it.
For me, conjurations are remembered when I am at some level of realization within the dream/internal experience, and the level of threat that I feel. There have been times when I felt threatened, had very strong lucidity and remembered to use a conjuration, which mostly just helped to abort out of the situation.
Since we are on a similar topic, if we find ourselves ingesting pills/drugs in the internal worlds, are these actual drugs and can they cause us harm as they would in the physical? Although I don't take such things now, in the past I have, I guess it's related.
That book looks interesting, does it help in any way reading it?