Michael Fassbender turned the Assassin's Creed set into paintball war zone once filming had wrapped.

The actor portrays Callum Lynch in the upcoming action film based on the video game of the same name, which also stars Marion Cotillard, Jeremy Irons and Charlotte Rampling.

Some of the film was shot on location in the Province of Almeria in Southern Spain, a spot made famous due to the number of Spaghetti Westerns shot there in the 1960s.

And on one occasion Michael decided to "treat" his colleagues to a game of paintball held within one of the deserted film sets.

"Everyone was working really hard, the stunt team was amazing and I thought as a treat I'd book the town and have a paintball shootout," he said during an appearance on The Tonight Show Starring Jimmy Fallon on Tuesday (13Dec16). "It was brilliant. We used the saloon as HQ, they have real alcohol in there... (But) booze and paintballing were probably not a good idea."

While Michael, 39, had a great time playing, he suffered a minor injury when he was shot by a high-power paintball gun at a close range.

"I got shot at close range...There are rules, you're not supposed to shoot somebody point-blank, but whatever, in the heat of the moment, battle is battle," he laughed.

"It went right up my face, it was like hickeys all the way up on my neck and I was bleeding from the forehead, I just saw white."

Following his interview with host Jimmy, the pair took to the stage for an intense air guitar battle.

The host kicked things off with The Boys Are Back in Town by Thin Lizzy.

But his moves were no match for Michael, who pulled out the big guns for Ozzy Osbourne's Crazy Train. He started by slipping on his "guitar" only to take it off for a quick change to bass when the iconic solo began.

"I'm so mad. I should have done more bits!" the host declared. "Well, you beat me, clearly, but for this last round how about an air guitar duet?"

The Steve Jobs star agreed and sat down to tune his "air banjo", much to the audience's amusement.