Brilliant Events are really smart Events that did a really good job paying attention in Arithmancy and brought home five or more Outstanding-level scores on their N.E.W.T.s.

Hold that thought, there may have been a slight misunderstanding.

Brilliant Events in Wizards Unite are special limited-time events that introduce a good amount of unique content into the game. Brilliant Events feature their own special Brilliant Registry pages, a list of Special Assignments, and a set of Brilliant Foundables that can only be encountered within the duration of the event. These Special Assignments are different from the usual Daily Assignments - they don't expire until the event ends. As you complete tasks, new ones become available, with some rewards like Restricted Section Books that currently can't be found anywhere else in the game, making Brilliant Events an enticing prospect.

UPDATE 6/27/19: The first Brilliant Event of the live release has been announced! See the Brilliant Event: Fantastic Flora and Fauna Guide for more details!