Expression based masks referensing other layers

Please make live mask with expressions  something like layer2A*layer3R / layer4G referencing channels of  other layers. 

I am so tired with doing copies of smart objects and putting them in clipping groups  that clipping another group  with channel mixers smart object adjustments   to extract red channels to be then put through Blend if  with black becoming transparent .  All this  makes a hell of a layer stacks and hidden clipping groups  I then couldn’t understand a thing within  just next day . 

No need for any nodes like in Nuke.  Just make  an expression driven layers  with explicit layers access.