How to create fading shadow lines over gradient

Question

I want to recreate this effect:

The gradient part at the very top of the mock-up has two line at the downside right-hand corner, with shadow over the gradient and fading inwards.

I want to recreate it with Adobe Illustrator only.

I found this on YouTube, but was not really able to achieve my goal.

Can you suggest the easiest way to achieve the effect above?

Answer 1

This example is made in three steps:

Background shape

• Fill color #5A00FF

Top shapes (grouped)

This is a group of three shapes made from a duplicate of the background shape

• Fill color #9057ED.

• They all have an Inner Glow Effect: dark color, mode Multiply, Opacity: 35%, Blur: 25px.

• The two top shapes are in Multiply mode at 40% opacity

• Select the three shapes and group them

Mask

• Create a Mask Shape a little bigger than the background shape with a radial gradient from white to black.
• Use the Gradient Annotator to transform the gradient area

• Select the group and the mask shape and align them
• From the Transparency Panel -> click Make Mask -> uncheck Clip
• This is the result:

• Select this masked shape and the background shape and align them:

• Edit the mask and modify the gradient to change the transparency