Over at the Five Star Production website, I noticed there's a teaser image for Art of the Devil 3, the sequel to 2005's Art of the Devil 2. It will again feature the work of the collective known as the Ronin Team, which on Art of the Devil 2 comprised seven director-screenwriters, including Kongkiat Khomsiri, who went on to pen the screenplay to Wisit Sasanatieng's The Unseeable and make his own solo directorial debut with Muay Thai Chaiya.
Though Art of the Devil 3 is the third in the Art of the Devil series, it is known in Thailand as Long khong 2, which I'm guessing will make it a direct sequel of Long khong, or Art of the Devil 2, which was a sequel in name only to the first Art of the Devil film, or Khon len khong.
Art of the Devil 2 was a different story than the first film. More of a psychological thriller than the posters let on, it starred Napakpapha "Mamee" Nakprasitte as a teacher who turns to black magic in revenge for a trick played on her by her students. She was a nominee for best actress by the Bangkok Critics Assembly, which was vindication for her being nominated as a best supporting actress for the Suphannahongse Awards - a tiresome, 2-year-old controversy that I don't want to elaborate any further on at this point.
What the two films do have in common is a set of some of the most graphic film posters ever. They probably inspired the posters for the Saw series.
The first two Art of the Devil films have been released on English-subtitled (and optionally dubbed!) DVD by Tokyo Shock and are available at HK Flix.