When you make a duplicate or create a new MGEF for a custom spell, there are things you can set such as;

Effect Archetype

Associated Item

etc.

Some of these are linked to each other, so if you choose:

Frenzy, Calm Archetypes etc they are linked to Aggression (which is greyed out)

The Light Archetype is linked to MagicLightLightSpell01, (but this is not greyed out, so you can change it to another one)

Other things have a Value Modifier which can be linked to Health, Magicka, Stamina etc.

Where can I find these Effect Archetypes and find out how they work?

Cheers!