How do I "mask" the bottom layer/object?

I know this question being asked a lot of times, yet I couldn't find a way for my solution.

The black box is the mask(name "Oil Masking"), and the layer below is the full oil inside the bottle("Oil on Bottle").

I want to show the remainig oil inside the bottle, minus the black box & the "block-outed" oil, so it will look like the oil is not totally full.

I tried many blending type but it just won't work. (I'm not totally understand this part) I just can't figure out how to solve this problem...

Help is so much appreciated.

The example blend modes from Construct 2 contains a visualization of the blend modes. So what you wanna do is put the black oil mask on the same layer als oil in bottle, put the oil mask above the oil (z-order) and set the mask's blend mode to destination out (if I'm not mistaken)

See: https://www.scirra.com/manual/146/effects #Blend modes

use blend modes on those sprites - out and in should do the work

Guys, thanks to your direction, I've finally figured this out!

mindfaQ: Thank you for your tips about putting the 2 objects in same layer. It's 'Source in' on the mask's blending, I have to put the mask's opacity to 0 first to work. ('Destination in' also works the same.)

And 'Source out' & 'Destination out' work in the inverted way.

Thanks!!