Trying to make a mask effect but I'm having trouble

Bumbles_McFumbles

Title says it all really. For an art project i want to mask out a checkerboard pattern on top of a circle with an odd shape. However it's exceedingly difficult as the built in effect masking isn't doing the trick. I was able to achieve the trick using cropping (https://streamable.com/b01dpp) but on anything without a flat surface like a circle I'm up a creek. I hope anyone here knows the software better than I do that might be able to help out.

borate

It's unclear - at least to me - what the elements are.

A Polygon mask can be drawn around any shape...

In this admittedly crude example mask and transparency are on track 2, the background is on track one. Mask OUTside is chosen.

Most any other effect, such as this animation, can be added after using the Clear Mask Effect button on the toolbar...

Mask.mp4