How to add a master reverb ?

This could be the right setup ? 
Yes, with mix knob in plugin i can adjust the amount of reverb
I need only the reverb on the master channel, but seems to be forced to add also the reverb on the aux channel too ( that is unneccessary ?) 
Or the other way around , a reverb on aux channel only? 

Also shouldn't matter if there is a reverb plugin on that aux audio channel: I make sure the audio signal is dry ( without reverb fx ) and then goes to the master audio channel where it can get reverb fx ( audio signal is wet).
You could also have an option on the aux channel that this output can be put to directly the master channel ( this is not the case for Synfire?)

Putting the fx on the aux module and leaving the master module empty would be more convenient and put the audio routing to the master, but from the looks of it this doesn't work.
The fx reverb aux output now does not go to the input master channel
 

From the looks of it the fx plug in does not seem to work in the aux module ?
But if I place the fx module in the master module, it will work.

Find it all confusing. 
In the online manual this is not explicitly mentioned that the output of the aux module goes automatically to the master module input .
On the master module this automatic routing is also not mentioned if the aux module has a fx set up