Cullen, 31, is arguably the most exciting fighter Scotland has ever produced. Certainly anyone who witnessed his classic bout with Paul Reed at SFC3 in 2010 would go along with that statement.
The Dinky Ninja Fight Team (DNFT) representative is a crowd pleaser. Not afraid to try risky techniques, Cullen would take a back and forward scrap over a stifling win any day of the week.
How exciting is he? Consider this ... none of his 15 professional career victories has gone the distance. That's 15 wins, 15 stoppages.
In Aberdeen on Saturday, August 31, he takes on Mariusz Abramiuk in a 145lb bout that promises to be an explosive affair.
Cullen, who is based at the DNFT's D-Unit gym in Dumbarton, said: "I have become so used to people saying that I'm an exciting fighter to watch and it's got to the stage where I don't want to disappoint anyone by being in a boring fight.
"I like that people say nice things about my fights.
"I'm an MMA fan myself and I like to watch exciting fights. I hate seeing matches where guys don't give it everything.
"If someone's going to beat me, I want them to work for it."
Cullen - who boasts an impressive record of 15-5-2 - is known for throwing high-risk techniques such as his favoured flying knee. But he insists the risk is minimised by how hard he works in training.
"I'll drill those techniques thousands of times," he said.
"I love flying knees, I throw one in every fight.
"But I'll do it 100 times in each training session so it's just like any other strike to me.
"I like to keep my game nice and exciting, it's what I love about fighting."
Abramiuk, from Poland, has been to Scotland before, famously missing weight ahead of a planned bout with Doni Miller at On Top 5.
The fight did not go ahead and Immortals will be hoping there is no repeat of that drama this time out.
After juggling a career in the cage with a day job as a mechanic, Cullen hung up his tools towards the end of 2012 to concentrate on MMA full time.
He believes fans will see the benefit of that decision when he fights Abramiuk.
He said: "I would have kicked myself if I looked back on my career and hadn't tried to do this full time.
"I'm at the age where it's now or never so I decided to go with it.
"I can train 40 hours a week now, rather than squeezing in sessions around my work patterns.
"I've been able to work hard on my wrestling and general ground game.
"I've watched some of Mariusz's fights online and I know he's a big featherweight with a good ground game.
"We have a lot of guys training for fights so this fight camp has been great. My team mates are brilliant and I couldn't ask for better coach than John Nicolson.
"I'm ready for this fight."
The card also features Artem Lobov v Kamil Gniadek and Maciej Linke v Alexander Proder, as well as a string of amateur bouts.
Immortals Fight Promotions takes place at the Beach Ballroom in Aberdeen on Saturday, August 31. Tickets, costing from £30 to £50 are available by calling 07834593580.