In Modul8 version 1 (1.1) there used to be 4 different blending modes for layers - normal, light, dark and exclusion. this are very powerful and useful compositing tools and could work much better than luma key in many ways.
Anyway - in version 2 they are gone! and nobody even mention them anymore (I actually hoped to see more of them in V2)
I find it a little weird that a feature is dropped when an update comes to a software.
Will they ever be back