If doing an Oracle-type thingy, worth researching how the atmosphere was cranked up by the priests in places like the Oracle at Delphi's cave. Approach was controlled, through long passageways with slots of dim light from the side, that became hypnotic as the devotee approached the dark cave, which had a smoky atmosphere. The questioner had to bring offerings, and couldn't approach the oracle him/herself, a priest was the go-between.