Sixstring
Legend!
This^^^I don’t think there is one and for me that’s the point. These Fractal devices are incredibly complex and so much thought and effort goes into among them what they are. If there was one magic thing it could be easily duplicated. It’s all these complex pieces working together.
Unless you are a single amp type of person there are so many different things to limit it to just one thing that can be a go to all of the time on every amp type.
That said if I had to pick one thing that is really useful in a multitude of tone shaping situations it would have to be EQ, pre and/or post.