Dragons hooker Mitch Rein says a licence to back his instincts is behind his strong early season form.

The diminutive rake is the fittest player at the Dragons and is averaging more than 30 tackles a match at an effectiveness of 93 per cent - a remarkable stat given he shares the hooking role with veteran Heath L'Estrange.

While no one's ever doubted the 25-year-old's defensive capabilities, it's his effectiveness with the ball that's had the biggest impact on his side's fortunes.

In eight games Rein has produced two tries, a try assist and a line break assist including a crucial close-range effort against the Roosters last week moments before the games was halted for 30 minutes due to a hail storm.

After initially being overlooked by Country Origin selectors in favour of Melbourne utility Ryan Hinchcliffe, Rein earned a call up to Trent Barrett's side on Monday as a replacement for the injured Jarrod Mullen.

He will join Dragons teammates Joel Thompson and Tyson Frizell in camp this week ahead of the match in Wagga Wagga on Sunday.

Rein said coach Paul McGregor's loosening of the attacking leash has allowed him to rediscover his running game.

"The way we were playing in the first two rounds wasn't really suiting us as hookers," Rein said.

"Mary's changed the game plan a lot and given us a bit more of a free rein which I'm loving at the moment.

"I love playing the open footy we're playing and the way our forward pack's going it's really helping us hookers and halves out a lot.

"If there's blokes pushing up around you, you can run the ball a lot more.

"We really worked on that after the first two rounds when it wasn't working for us, we wanted to get a lot more push around the ball.

"Most teams do it but we were a bit slack in that area.

"We've really picked that up and I'm really enjoying the footy we're playing."

As he closes in on 100 first grade games, Rein said the win over the Roosters in trying conditions rates as one of the best in his time in the Red V.

"It's pretty high up there," he said.

"Everyone knows the Anzac Day game is played with heaps of emotion and both teams put in 100 per cent.

"Especially with the Roosters coming off three losses. That doesn't happen very often.

"I've never played in a game like that before.

"I think we warmed up about five times, so it was pretty weird but we've played a few games in the wet so far this year in England ... so we're used to it."