Shaun Kime, Epic Games

I’ve created the following system:

I used the + button next to System Exposed Parameters to add the three user variables shown at the top. By virtue of being in the User namespace, those variables will now be tweakable per instance in a level. Here you can see the three places the User variable has been bound in the stack:

If you drag into the world, you can see these parameters are also editable in the level via the property editor for the actor:

Here’s a sample level Blueprint that sets the user color to a Blueprint variable, the user spawn rate to a constant, and the user position to the value of a Sphere actor in the level:

Source: Niagara Blog