ID Mask in 2.8

Support Compositing and Post Processing
1

How to use material index? I can’t find the Index input.

2

For Cycles, it is obsolete since Cryptomatte support.
https://wiki.blender.org/wiki/Reference/Release_Notes/2.80/Cycles#Cryptomatte

Unfortunately, Cryptomatte is not available for EEVEE. And material index pass was not restored for EEVEE by lack of time.

3

I need it in Cycles. The problem is I making lamp. This is a transparent object. I can’t separate the light out of the glass.

4

I made a mistake.

Material Index Pass is still there for Cycles.
Into Passes panel, it is under Data subpanel.