There isn't many impressive Thailand movies, except a few. Art of the Devil 2 is really impressive and shocking. Part 3 will not disappoint since this is the No 1 movie in Thailand.
A BIG BIG WARNING to you before you click on watch on the following trailer. Although unrated, I strongly suggest you DO NOT watch it before meal or sleep. Also, If you are under 18, please do not watch this as well. You have a happy life, don't let me ruin it for you by showing you the dark side of humanity. :)