Here’s something for you synth programmers to try out: Modulate certain aspects of an envelope with itself.
For example, set the modulation destination of the filter envelope to affect its own parameter, such as its (linear) attack or decay time, by a positive or negative amount. This should render a concave or convex shape, respectively.
This effect is referred to as recursive modulation.
Now try to set filter envelope attack to 32, and envelope amount to 48. Then go to the modulation matrix and select the filter envelope as source, and modulate the destination filter envelope attack by 48.
It’s also possible to use this method on a LFO. Modulating its own level will also affect the shape of the LFO. And by modulate its own rate, will affect both the overall rate and the shape.