Vengeful Viola by Karoryfer Samples. Violas are supposed to be warm, friendly and docile. This one isn’t. There are noises like bowing the body, screeching unclean harmonics, very bright sul ponticello… And also phat sustains and sul tasto sustain and staccato, to balance things out.
Layering multiple articulations and creating emulated small sections by using unison mode are included, of course.