With these direct-to-video movies starring Scott Adkins, I generally have an idea of what’s coming: decent to excellent action sequences combined with a pretty standard and predictable plot. Occasionally, though, one will surprise you, and DIABLO is the latest example of that. Adkins delivers a performance consistent with his usual style; he's not bad, but he doesn’t particularly stand out either. Still, as has been demonstrated previously, when Adkins gets good material to work with, he can be effective. That isn't true for Marko Zaror, though—he is undoubtedly the best part of the film. He portrays a truly frightening and intimidating slasher villain, while also showing some unexpected comedic talent. The fight scenes are among the strongest featuring both Adkins and Zaror, not just in terms of martial arts choreography but also in their larger action set pieces and gun battles. The standout moment is Zaror’s incredible slasher-villain-meets-RoboCop shootout sequence. There's a distinct change in feel when the movie moves from calmer moments to action sequences. I will say, this issue lessens as the film progresses. The quieter sections in the first half did make the overall experience feel somewhat slow and disconnected. Fortunately, once the action begins and Adkins’ and Zaror’s characters come together, the movie really hits you with a blast of entertainment, compensating for many of its shortcomings.

Source on TMDB