Reduced mana cost math.....

What's the relationship with mana cost multipliers on support gems, and the "reduced mana cost of skills" passive nodes?

I assume all the mana cost multipliers are multiplied with the base mana cost, then the reduced mana cost passives are multiplied by that resulting value?

For example:

Greater multiple projectiles has 200% mana cost multiplier.
Added cold damage has 140% mana cost multiplier.

If you are using these support gems together with a spell that has a base cost of 10 mana, then it will actually cost 2*1.4*10 = 28 mana

Let's say you then pick up 3 reduced mana cost passive nodes. 2 worth 5% each and 1 worth 10%, totaling 20% reduced mana cost. This is then multiplied with the previous result to get the new final cost of the spell.

0.8 * 28 = 22.4 mana

Is this how it works? Or are these mechanics wrong?

Sorry if I'm not making much sense I'm pretty sleepy.

yes, this should be how it works. (you can also put it in the equation like so and get the same results: 2 * 1.4 * 10 * 0.8 = 22.4) make sure you don't confuse the "mana reserve" (the one that reduces the cost of your auras) and the "reduced mana cost of skills", though cause then you'll just feel like an idiot... (speaking from experience...) -_-

glhf