Lucidity
The Oneiros may percieve the dream of a sleeping target. After making contact with that dreaming state the Oneiros may alter the details of a dream.
System: Difficulty to perceive the dream of a sleeping target is 6. Then should the Oneiros decide to alter the details of the dream (i.e. use it to communicate with the sleeper) then the storyteller sets the difficulty based on the extent of the desired changes. Allowing the Oneiros to step into the dream if the target doesn't know him or her the difficulty is 6, changing the setting is (from a pool party to a swamp) is a 7. The player rolls manipulation + Phantasmagoria rating, the change becomes more vivid and lasts longer for each success.