c4d's taper is different as I assume you know. You could do something similar with a Loft - copy the spline and lift it then you could rotate the upper spline to get the same thing but do do it with a deformer it looks like an FFD with only 2 grid points in X/Y/Z to make a simple box then select two of the corner points and drop them. Or select all 4 top points and rotate - which looks more like the max taper.
You might also need to subdivide your inner most object (either by making it editable or by upping the divisions in the spline and the extrude) otherwise you might get "bent" polys from certain deformers. It all depends on whether the deformer subdivides before or after the warp.