The Dragons young guns earned a place in the showdown at the Gnoll in Neath (kick-off 2.30pm) with a superb victory against their counterparts from the capital on Wednesday evening.
They triumphed 28-12 at Cross Keys' Pandy Park with prop Leon Brown, wing Lloyd Lewis, back row Harrison Keddie and scrum-half Owen Davies crossing the whitewash.
"It's been a difficult year with some good results and some bad but the boys have worked incredibly hard," said Dragons Academy manager James Chapron.
"We've used a large squad but the management team of Bryon Hayward, Rob Sidoli, Lewis Evans, Dai Flanagan and Angie Prangell have done a great job because we have 10 first-year under-18s and that's really positive ahead of next year.
"The Blues are a very good side and will no doubt make some changes from midweek but the boys can take a lot of confidence from what was a superb performance."
