Brigganocks are frantic, mouse-sized creatures that live in mines. Whenever a mortal makes a nonmagical wish, perhaps while blowing out the candles on a birthday cake or tossing a coin down a well, an echo of that wish becomes lodged in a stone buried deep in the earth of the Feywild. Brigganocks seek out these wish stones, discarding the ones that contain wishes of ill intent and keeping those that hold good wishes. Brigganocks refine wish stones into gems and use them to decorate their architecture and crafts, or they trade them to other Fey for food and favors. A more powerful Fey creature can use a wish stone to scry on the maker of the wish, empower a supernatural charm, or provide the spark needed to create an animated object. Other uses are possible as well.

A brigganock's soul lives outside its body, manifesting as a bulb of pale light that floats alongside it and helps the brigganock see in the dark. Brigganocks have minor spellcasting abilities that help them survive. They also have the ability to manipulate time, allowing them to accomplish hour-long tasks in a matter of seconds, though a brigganock must rest between these bursts of temporal acceleration.

Brigganocks like to nibble on cheese, lettuce, and other soft foods. They eat quite a lot for creatures of their size and never turn down a good meal.