Sandmaster

Sandmasters are the unnatural inspiration behind stories of genies. They have an elemental mastery of sand; able to attack with living sandstorms or form it into palaces at will; and they also have a kind of telepathic illusion: they can shape sand into anything you can imagine, and make it seem completely real. But they have no imagination themselves, and so can only create things they've actually seen unless there's a human there to do the imagining. They often appear the people lost in the desert, offering a banquet at an oasis, or a mysterious palace hundreds of miles from civilisation.

These feasts taste completely real, and a sandmaster can gain sustenance from it (though their energy actually comes from the spiritual energy of the person who imagined each item for them). As for the people who join them for dinner… the meal tastes great (if a little dry), and the wine is refreshing, but as far as nutrition and health is concerned, they've been eating and drinking sand.