I found that damiano's defense gives a brilliant move in two moves.
What is the fastest brilliant move you can get in a game?

FYI: The legendary knight sac in the Daminao Defense allegedly stops receiving a "brilliant" tag when you reach a certain ranking. It's a common pattern and pretty well-known by anyone who is at least decently experienced with the game (plus, virtually no one past "complete noob" skill level plays 2. f6 anyway), so it kind of loses its value as a result.
here is the fastest brilliant move I think (it's the knight sack it opens up the queen)