In March last year, the double-header event was held for the first time, with the Ospreys beating the Blues 23-16 and the Scarlets toppling the Dragons 28-20.
More than 36,000 fans went through the turnstiles for a showcase that lived up to every inch of its billing. The success of the day naturally ensured it would not be the last time it happened and that next month's follow-up is being even more keenly anticipated.
This time around, the Blues will tackle the Scarlets before the Dragons face the Ospreys as the two teams from the East go in search of revenge and, as ever, the two derbies offer the potential for some explosive individual duels.
How will old maestro Gethin Jenkins fare packing down against one or other of the Scarlets' emerging tighthead props Samson Lee and Rhodri Jones? Can the youngsters in the Blues midfield cope with the threat of a fit-again Jonathan Davies?
The clash between the Dragons and the Ospreys will also see some intriguing issues settled.
Can Toby Faletau and Andrew Coombs rally the Rodney Parade eight to deal with an Ospreys pack that is still one of the most feared in Europe? And will the goalkicking of Jason Tovey keep pace with that of dead-eyed marksman Dan Biggar?
Winning personal battles usually leads to team success and all four sides will head into the afternoon having not had enough of that for their liking so far this season.
Unfortunately, as things stand now, it is only the Ospreys who harbour realistic hopes of making the end of season play-offs. With ten wins from their 17 outings, Steve Tandy's men are tucked in behind leading trio Munster, Leinster and Ulster.
Not that there isn't a bundle of professional pride - as well as those bragging rights - to play for. Just four points separat the Blues and Dragons with both desperate to avoid finishing as the worst-placed Welsh side.
Looking ahead to Judgement Day, Taulupe Faletau said, "It'll be great to go up against Ospreys and it's really exciting for the players and the fans to be at the Millennium Stadium. With all four regions in one place, and the great support of our regional rugby followers, it's going to be a fantastic occasion and all the players will be looking forward to it."
Tickets are available from wru.co.uk/tickets or from all four regions.