How could an organism (anywhere from animal to monster to humanoid) induce and control lifelike hallucinations simulating reality in (possibly unwilling) humans?
The aesthetic thought was of a monster (or whatever) surrounded by humans who are experiencing some form of simulated reality while laying in a puddle of chemicals around the monster.
Preferably the humans would be relatively unharmed once the creature released them from their experience.
This would be set in a world mostly similar to ours (no magic), but would be set in the future and would very likely feature extraterrestrial life.
Specifically, I'm interested in how and in what detail could the perceived realities of the dreamers be controlled?