If a person is wearing ultrasound goggles, on the other hand, they would still see a manifestation, because it is projected directly into their mind, bypassing their eyes. In fact, that brings up an interesting question: Can blind/deaf people still see/hear mental illusions, such as those caused by mana illusion spells and manifestations?

I thought of another cool spirit trick. Materialize a spirit out of raw sewage, and use the engulf power with it.