Vin Diesel had to attach a propane tank to his back for the flaming sword

SUMMARY

Vin Diesel wanted to use practical effects for his film
His flaming sword was created with a propane tank attached to his back
His character was inspired by Dungeons & Dragons

Vin Diesel once starred in an action/fantasy film back in 2015 that bombed at the box office. Portraying the role of Kaulder, Diesel starred alongside The Lord of the Rings star Elijah Wood in the 2015 movie The Last Witch Hunter.

As the name suggests, Vin Diesel is a witch hunter who is on a hunt for the Witch Queen. With opting to use practical effects instead of CGI, Diesel revealed that he had a propane gas tank strapped to his back for his flaming sword in the movie and he was very much scared of the possible explosion!
Vin Diesel in The Last Witch Hunter (2015)

When Vin Diesel Was Afraid of A Propane Tank

Although the actor should be all too familiar with fuels and tanks considering he has portrayed the character of Dominic Toretto, Vin Diesel never had a propane tank strapped to his back before. Starring alongside Elijah Wood in the 2015 film The Last Witch Hunter, Diesel was quite happy with the end product.
Vin Diesel in a still from the Fast and Furious franchise

Throughout the film, the XXX actor was seen brandishing a flaming sword in his hand. Well, turns out the sword was actually a real sword that was kept on fire through a propane tank attached to the actor’s back. Talking about how they had to pay special attention to the practical effect at hand, Vin Diesel stated in an interview with Vulture that he was deadly afraid of the sword burning his fur or face!
“The most dangerous part was going from the stunt sword to the real sword. If you tilt the sword, the flames would threaten to burn you. And the beard and the fur, that’s what was so scary. There’s a propane tank strapped to your back and you look to the left and there are eight firemen, and you suddenly realize there’s not a lot of room for error here. You will go up in flames.”
Well, it seems that Vin Diesel took a board game quite literally since he revealed in an interview that his character of Kaulder was inspired by his personal character in the iconic board game, Dungeons & Dragons!

Vin Diesel Was Inspired By Dungeons & Dragons

Elijah Wood in The Last Witch Hunter (2015)
 

As the interview continued, Vin Diesel let his geek side out as he revealed to Vulture that he was a fan of the iconic board game Dungeons & Dragons and that his character was inspired by Diesel’s in-game character Melchor (which he picked from the world of J.R.R. Tolkien)
“I guess I’m safe in this room — it’s no secret that I love Dungeons and Dragons. I actually had a character that was a witch hunter. Elijah will know where this name [Melchor] is from, I stole the name from a popular author. Straight out of the Silmarillion.”
The 2015 film received a rating of 5.9/10 on IMDB and a record-low of 18% on Rotten Tomatoes and managed to earn average earnings at the global box office, The Vin Diesel and Elijah Wood starrer is available to rent on Apple TV+ in the U.S.