I went over a few scenarios and had a few other people try it out as well, and I can confirm that CP is
additive with other modifiers, rather than multiplicative.
Here are the conditions used. This is MS + SS + Zaan running Inner Light on the front bar.

These are the expected values we should see for our Max Magicka for both additive and multiplicative CP modifiers.

Here is my Max Magicka with the Mage Mundus

Here is my Max Magicka without the Mage Mundus

As we can see, it appears that CP is interacting with other modifiers on an additive basis, rather than multiplicative. This doesn't mean much for stamina, since your Max Stamina modifiers are usually pretty small. But for magicka DPS, this does mean we're losing ~1k Max Magicka compared to what we initially assumed (multiplicative modification).
@ZOS_GinaBruno @ZOS_JessicaFolsom Can we confirm whether this is intended or no?
Edited by T3hasiangod on February 11, 2019 10:03PM PC/NA - Mayflower, Hellfire Dominion
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