[JohnFen]

A brilliant dev is one who consistently produces solid and feasible solutions to difficult problems, in a timely way.

A more enlightening question is "what is a rock star" in my mind. A rock star is a dev who truly believes that they are the smartest person in the room, who looks down their nose at any work they didn't produce, who is only really interested in things that they think make themselves look better rather than things that will actually help produce the best end product possible, who insists on using the whatever latest shiny thing is in fashion over less shiny but more appropriate approaches, and so forth.