I don't think worship is the only way it can happen, but I'm pretty sure the gods draw their power from mortals. Almost everything else in the Dresdenverse does.
That's what the fey have that stone table for.
That's cool stuff.
But honestly, I don't think you really need all these new Powers. (Sorry.)
...
I think some of that is a difference in our approaches to the rules though. I prefer to use canon powers when at all possible, and use custom powers only for genuinely new effects (except for Demonic Co-Pilot which is just bad ... although Feeding Dependency may be joining that list).
Thus I prefer The Catch to Limitation, I prefer to use Physical Immunity costing rather than Immunity costing for most situations, etc.
You don't need to apologize.
And yes, it's a difference of approach. I'm pickier than you are, when it comes to balance. And I suspect that you're less enthusiastic/comfortable about replacing rules than I am.
(You should add Feeding Dependency to that list.)
I have a pretty full writeup of Lea somewhere, and I've been doing some rough working out in my head for how I think Mab would look, and I don't think she really needs any new powers except a "Domain" power... and your Divine Domain looks good for that.
I vaguely recall liking your take on Lea. But I think Mab definitely needs new powers. Here's why:
Mab is capable of defeating the entire White Council single-handedly. And there is no level of Toughness that will let you tank hundreds of death curses or thousands of evocation attacks. Legendary skills and Mythic powers across the board would be laughably insufficient if the whole Senior Council started blasting you.
So she needs a custom Power. Either Immunity or some new level of Toughness. I went for Immunity because I didn't want to deal with the massive numerical inflation that her Toughness would require. Plus I already had Immunity written.
But that would make her immune to other gods. So she needs some way of being harmed by them. I'd rather have the methods of harming her be on the character sheets of opposing gods rather than on her character sheet, so I went with ACaEBM.
That method also has the advantage of making gods more effective against mortals...I think gods should be able to casually kill mortals no matter how tough they are, and I'd rather not raise their numbers to the twenties to represent that. Plus I already had ACaEBM written.
Divine Toughness follows in a fairly obvious fashion.
There are other ways to do this (for example, I could give her Immunity to everything except the attacks of gods and Mythic+ Toughness/Recovery) but I like this method best.
As for Miracles, well...it's basically just spellcasting without the drawbacks. No item dependence, no mental stress, no need for three different skills. Spellcasting has a lot of trappings built-in, and most of them aren't appropriate for gods. Removing them one by one would have been a hassle, and this seemed easier.
(The skill number is the most important issue, by the way. I don't want every god to have the same three apex skills.)
Sound reasonable? If not, what do you think I should change?
And just out of curiosity, what's your beef with ACaEBM?
(There are broader questions about gods' power in the NN vs mortal world and how that should be modeled in the game, but those issues aren't unique to gods -- same would apply to any 'ectoplasm body' demon/spirit/summoned creature, though for slightly different reasons.)
Yeah, the Nevernever in general is confusing like that.
DOUBLE EDIT: I also think that gods in the Dresdenverse tend to retain their "normal" weaknesses, at least if they come from a "type" that has them (Mab flinches from iron, and Jim has said that an ordinary mortal at least theoretically could kill her under the right conditions -- a chance e.g. the Erlking wouldn't). There's also a WoJ that when those cosmic beings enter the mortal world, they become somewhat vulnerable themselves. So immunity to mortals is I think too much -- it's just that their power and awareness are so great that it's really unlikely for anybody without comparable power to get into a position to harm them.
I'd rather handle that with Aspects.
I mean, hypothetically a mortal could wound Mab with iron. But in practice, attacking her is pointless because she'll defend against everything casually. Unless there's something plot-ish going on.
So when her weaknesses come into play, she can just get Compelled.