Maths

Please describe any possible scenarios for using that? Thanks.

You can use it as a wave shaper, or use it to add crazy amounts of gain.

If you wanted to automate level or left and right channels individually you could do:
l = l * p1
r = r * p2.

Swap left and right channels:
l: r
r: l

Make mono:
l: (l + r) / 2
r: (l + r) / 2

Invert polarity:
l: -l
r: -r

So one should really read the manual to uncover which functions you could use/modulate and understand if it's helpful for him, right?

There is a list of available functions, constants and operators here: http://socalabs.com/developer-tools/maths/

is this plugin written with Faust? thx.

No, C++ / JUCE.