Best Method for scope control?

When dealing with blends (not surface/curve) of features, as an abstract, what is the best path to controlling scope?

What I mean is, lets say you have a simple map to surface (here Im using thicken) and you would like to programmatically apply a ‘fade’ from the bottom edge eg 0% and the progressing to 100% at the upper ring?

Sweep, deform, attributes, attractor, field, simulation, mesh smooth… It depends on your situation.