slices

[VJ_Lazershaft]

possible to have multiple nested masks per slice?

would really help with some slice transform effect stuff too, alternatively, (or additionally) having an option in slice transform effect to apply it as an actual blackout mask (NOT the mask option...)

[Zoltán]

Indeed, currently you can only have one Input slice mask.
You can draw it with a pencil though.

If you need such complex masks you might be better off drawing the slice itself with the polygon tool, or applying the masks on the clip or layer level.

If you could let us know more about what you are trying to accomplish, that would be a great help trying to understand your workflow, and we could maybe figure out a proper solution for it.