Its just in the build planner atm, haven’t rolled it up yet. I am guessing its Option 2, but I am not sure how it works exactly. I might scrap it if it’s Option 3 or worse.
I couldn’t find a more updated source on this, but this post gives you an idea of what mana efficiency does.
If this formula is still correct, then none of your formula’s are correct.
Additionally, I would think that the rest of the calculations behave similarly to how they work for damage, but I’m not sure. But, with this information, you should be able to test that theory with concrete values and figure it out.
I have a guess of what it might look like, but I don’t want to speculate.
You could also look in the game guide there might be more information there.
Game guide doesn’t specify anything different for mana costs, which is why I think generally option 2 is correct. But the mana efficiency is…um… really badly worded/presented.
If its true, then Option 2 becomes:
Option 2: (18 + 30 - 11)) = 37 * 1.75 / 1.75 = 37
Which would mean I wouldn’t even bother making the build at that mana cost.
I have only 2 points in Forested Expanse, meaning +2 totems (total 4), or +50% cost (x 1.5). But then -1 max totems from Grove Mind, or 3 total, +30 flat mana cost.
Also, I forgot to initially factor in that Shaman get -5 Totem cost as a class feature.