White Room
The user creates a mental room (like a dream) where any memory can be projected. Inside the room any physical effect (injuries, training, pain) has no effect in the real world, but mental ones yes (stress, technique, nen training - some of them).
Two more people can enter this room by touching the main user if this one desire it. The memories of the external ones can also be projected if they decide to share them. They can also use their nen abilities as normal, but the effects will be like a simulation.
The time inside this room goes like x100 slower compared with the real one. A perfect place to talk, train and not loose time.
Water Divination: the water stays calm against any shake or disturbing effect.