We’re still a year away from being able to watch the eighth and final season of HBO megaseries Game of Thrones, but it appears the cast and crew aren’t wasting a moment of that lengthy lead-up.

Assistant director Jonathan Quinlan has whipped fans into a frenzy by sharing – and later deleting – a photo from the show’s set that hints at the creation of the most epic battle scene in the program’s history.

The April Instagram snap shows a printed poster bearing a thank you note to the show’s team from the so-called “producer types”.

“This is for the Night Dragons,” the note begins. “For enduring 55 straight nights. For enduring the cold, the snow, the rain, the mud, the sheep s––t of Toome and the winds of Magheramorne.

“When tens of millions of people around the world watch this episode a year from now, they won’t know how hard you worked. They won’t care how tired you were or how tough it was to do your job in sub-freezing temperatures. They’ll just understand that they’re watching something that’s never been done before. And that’s because of you.”

Quinlan captioned the photo: “Says it all. 55 consecutive nights. 11 weeks. 3 locations. You’ll never again see anything like it.”

The note for Game of Thrones‘ cast and crew, shared to assistant director Jonathan Quinlan’s Instagram page.

According to fan forum Watchers on the Wall, the note comes after months of night shoots at two locations in Northern Ireland – the Winterfell set in Moneyglass and a massive green screen set in Magheramorne. The aforementioned third location remains a mystery.

The HBO series is infamous for its high-budget battle scenes, like season six’s Battle of the Bastards, which featured 500 extras, 300 crew members, 70 horses, extensive CGI, took around 20 days to film and was estimated to have cost more than $13 million ($US10 million).

More recently, season seven’s Loot Train Battle took 18 days to film and featured 60 horses, requiring precise choreography for the many stunt people involved.

Most shots also had to allow space for a CGI dragon which meant, according to the episode’s director of photography Robert McLachlan, every shot was “budgeted to the second”.

“It’s so wildly expensive to create those images,” he told The Hollywood Reporter.

There is a lot riding on the final season of Game of Thrones, which is HBO’s most popular show, especially after the writers veered away from the original source material – author George RR Martin’s trilogy of fantasy novels.

But according to actor Iain Glen, who plays Ser Jorah Mormont, the finale will deliver the goods, eight years after the show’s first episode premiered.

“I am one of the few people who has read the script and I know the ending and what happens,” Glen told The Indian Express.

“When I read it, I thought it was rather brilliant. I am a bit of a fan of the series as well, and it satiated my expectation and hopes.”