What I am trying to achieve is create a universal variable in salesforce which I can access in my assignment rule.
I will set that variable to some value through UI. Assignment rule will check if that variable is = xyz then assign to queue1 if that variable is = abc then assign to queue2 ... and so on.
So which functionality in salesforce should I use to create a variable and access it in assignment rules? Will custom setting do? I am not sure about this because can't access list custom settings in assignment rule criteria formula.