While the Masterpiece line has tended to focus on prominent characters that appeared in the Transformers cartoon, the same need to maximize the return on the costs of producing molds that applies to standard toylines also applies to the Masterpiece line. Perhaps even more so, given the costs inherent in producing such high-quality figures. This explains why comparatively obscure characters such as Artfire get featured in the Masterpiece line before arguably more-popular characters who would have required the construction of all-new molds.
Masterpiece Artfire homages a character from the Japanese Headmasters toyline, created just for the Japanese market and never sold in the United States. Just as Stepper/Ricochet was a reuse of the G1 Jazz mold, the original Artfire was a reissue of the G1 Inferno mold with a few modifications to give the toy a Targetmaster weapon (called "Nightstick" in Artfire's case). That original version of Artfire has, rather surprisingly, never been reissued to this day, even though other versions of Inferno have gotten repaints as the Artfire character.
For the most part, Masterpiece Artfire could be created simply by giving the Inferno mold new colors (in truth, Artfire uses some elements of the Masterpiece Grapple mold, but these are fine details), but whereas the original Artfire could be given a Targetmaster weapon simply by repurposing the Targetmaster partner given to Scourge in the United States (Scourge was never sold as a Targetmaster in Japan), an entirely new mold had to be created for this diminutive figure for the Masterpiece line. In fact, although Hasbro had created a Targetmaster partner for their version of Masterpiece Rodimus Prime, Takara had never done a Targetmaster for a Masterpiece figure before, making Masterpiece Nightstick unique.
Like Inferno, Artfire changes into a fire truck, and Takara took advantage of the opportunity to add some extra compatibility to the Targetmaster accessory. By attaching a peg on the arm of Nightstick to Artfire's ladder, Nightstick can ride along and offer some action poses. Alternatively, he can peg onto the back of the ladder or on top of the cab in weapon form (Readers are encouraged to check out the TFWiki entry on Artfire, as well as Sixo's review of the MP Artfire figure. Thanks to both sites for the pictures linked in the previous sentence).
A peculiarity of the Targetmaster characters depicted in Japan's The Headmasters series is that the Targetmaster weapons actually fuse themselves to their partners' arms, replacing the partners' fists entirely (this is despite the fact that the G1 toys for each of these characters held the weapons in their hands like everyone else). Although Artfire never appeared in the cartoon (and, to the best of my knowledge, never demonstrates the weapon-arm in his sole appearance in contemporary Japanese manga), Masterpiece Artfire does allow for this feature, but you're still able to place Nightstick in Artfire's fist if you prefer.
Masterpiece Artfire retains other gimmicks created for the Inferno version of the mold. Here we can see two of them: either of Artfire's fists may be swapped out for a laser, and Artfire's face may be swapped out for a less stoic expression. All told, these make the figure a worthy addition to any collection, even if Artfire admittedly is a lesser-known character.