Alpha Mask Support
Having the ability to use a mask with opacity is pretty basic. This feature has been in Illustrator since the beginning... Photoshop (of course with alpha masks) - it's in Sketch (mask mode > alpha)... pretty much all the apps... but not in XD? Why? Very strange.
Franco Calcagni commented
Please allow the alpha values in masking so we can have a gradient mask or mask with feather borders, this feature is already present in all graphic tools of adobe (illustrator, photoshop and even Fireworks), this is essential for have a simple workflow without the need to switch back and forth between many applications in order to get that basic result.