For the first time the Welsh regions will go head-to-head in a double header at the Millennium Stadium this weekend and each of the regional coaches today agreed the roof should be closed for both encounters.
Coombs, who starred for Wales during their successful RBS 6 Nations campaign reckons the decision will please the players and supporters alike.
"It's great that the roof will be closed," he said.
"There is nothing else like playing at the Millennium Stadium and when the roof is closed the noise is just incredible and that sets Saturday up really nicely."
"It will be a fantastic occasion for the fans, the players and everyone involved.
"Hopefully the supporters will turn out in their thousands for what is going to be a big day in Welsh rugby.
"The performances from the Welsh team recent really brought the nation together and the weekend will be a chance for the fans to come here, enjoy the setting and have a good day out."
Coombs made his debut at the Millennium Stadium back in the opening Six Nations encounter against Ireland and won his fourth international cap against England in the Championship winning match.
He missed the Dragons' defeat to Ospreys last weekend due to illness and is looking forward to pulling on the Dragons jersey again.
"I've got a big role on Saturday and need to carry on from where I left off with Wales and try and lead by example," he added.
"I'm looking to put in a big performance it's these games you really look forward to, the big days in Welsh rugby.
"Not so many of our players have played at the stadium and it's going to be a fantastic stage for them to play on and the whole squad is looking forward to it."