This effect sends a message in chat for the volib.lua Figura library to catch and use to trigger things to happen on your Figura model. You can find this library and usage examples in the Discord server at this thread.
In more technical terms, it lets you create custom events for volib.lua to listen to.
If you are given a model that is supposed to use this effect, follow given instructions by the model creator on how to set it up.
Action ID - The ID you will use to refer to this effect in your Figura script.
Extra Data - Any extra arguments that the Figura script requires. Syntax is var1value;var2value;var3value as an example with 3 values. Placeholders can be used in this field in order to get dynamic data.
Rub Trigger or a
Struggle Trigger to make the stomach shake when prey rub or struggle from the inside.<uprey>;<zprey>;<hprey>;-;12;125