Faith:
While technically you are an energy being more akin to a Star Trek/Stargate Ascended than a conventional deity, your Frankenstein-esque nature means most forms of energy are compatible with you. Including Faith, which is essentially radiation here. Something about sapient life causes it to generate much more energy from thought and emotion, and makes faith a viable energy source for you. Your 'High Priest' is special in a number of ways. Regarding Faith, normally, you'd earn 1 Faith per 3 months. A High Priest earns 1 Faith per day, and has a much lower threshold of belief to count as a follower. It helps that the choices available are all warm, friendly people who form bonds quickly when reciprocated. Meaning you start with an income of 91 from the one person per Turn.
Faith can only be harvested from people who hold a certain amount of belief in you, though there are Perks and Domains that can lower it. This also means that failing enough times or catastrophically enough can lower Faith by losing you followers. Generally speaking, you need to be alive to produce Faith, though a particularly potent and lifelike ghost can be an exception.
Faith costs scale per level of a Domain, but so do the benefits. For instance, Mushrooms would go 5, 10, 15, 20, 25, then the rate doubles on the fifth level. 35, 45, 55, 65, 75. 95, 115, 135, 155, 175. And so on. As a general rule, once you hit Tier 15 or so, you should only expect major benefits as of every fifth Domain level, though they do still ease Action DCs.
For instance, in the Ben 10 series, the Omnitrix has a lock with 10,000 possible combinations. Ordinarily, this could be brute-forced fairly easily by equivalent technology, or a Spark of Creation such as yourself. Of course, with no relevant Domains or Perks, you'd be rolling a 1d6 per Action against a DC of 100. With relevant Domains like Technology and Programming, you can bring that down, as well as increasing the d6s you're working with.
Domains:
It might be best to define these as being akin to Apps on a phone. They dramatically streamline relevant processes, though only for those things that are, indeed, relevant. For example, Mushrooms would cost 5 Faith to purchase it's first level in, but you wouldn't be able to use it on, say, moss. Fungus would cost 10 Faith for it's initial level, but wouldn't be as effective on Mushrooms as the more niche Domain. Domains provide both an easing of related actions directly, akin to turning a screw with a screwdriver versus barehanded, and by improving related knowledge. See above. Domains with similar meanings usually complement rather than overlap. Creation is ex nihilo creation, where Crafting manipulates extant materials, and the two work well together. Salvage and Loot generally refer to very different circumstances, but any time you would Loot can technically be considered salvaging. Martial Arts and Sword-based blessings synergize, as does Art where Painting is concerned.
Domains escalate in cost as they grow more broad. Do note that incredibly broad Domains like Omnipotence and Omniscience are technically available, but you'd need double digits in them to get any real benefit. In essence, they're too broad. It's the opposite issue to a swiss army knife. You have 5 Domains like Cars, Swords, or Painting, 10 Domains like Machines, Weapons, or Art, and common Domains end with 15-Faith Domains like Technology, Equipment, and Creativity. Then there are the 20 Domains. These tend to be Meta-Domains. Faith, Empowerment, Action, etc. They are useful for much on their own, but they make you better able to do types of things. Faith, for example, is the best way to lower the necessary amount of belief to form and maintain a connection with someone, though it would take double digits to make people start producing more Faith directly. 25 is where 'genre' Domains sit. Things that define a setting. Warhammer 40K would have Chaos, Psi, and Heroism(struggling against impossible odds for just one more day), for example, where Star Trek would have Mundane(in the sense that the idea is that we could one day achieve all of this ourselves) and Wonder, Persona has Order and Chaos, and Dragon Ball would have Qi and Heroism. These are Domains that start providing major benefits to both you and your followers automatically unless you restrict it for whatever reason, and synergies with your choices and any power-ups you hand out only compound them.
Due to Chaos and Order technically being moral alignments, they don't quite function like normal genre Domains. They have different Faith costs, and tend to be something used in tandem/as a steroid for another power. For example, Chaos 1 is a 1d6 cost, Chaos 2 and 3 are a 1d36, Chaos 4-6 are a 1d216 apiece. Order, meanwhile, is a straight 5 as of it's first level, 25 at level 2 and 3, 125 at level 4-6. Chaos can push up the strength of a Magic spell or a Qi technique two orders of magnitude, but at the cost of instability and random effects. Say you wanted to make a chicken lay more eggs. Maybe you get exactly what you want, more likely, one of the following effects will occur. Perhaps the chicken will start laying eggs so fast it more closely resembles a machine gun than a normal chicken. Maybe the chicken will turn into a giant human-eating mutant whose offspring are similarly changed. Maybe you'll create Mega-Ultra-Chicken, the God-Emperor of Chickenkind. Or the chicken might just get palette swapped. Order only does a single magnitude, and makes the spells more rigid. For example, having a bolt of electricity jump into a powerline after missing it's mark, drain a chunk of energy, and then jump back out to hit the enemy from behind? Normal or Chaos Magic could do that, but Order Magic could not. On the other hand, you can get a singular magnitude jump, while not having anything weird happen.
Finally, there are 50 Domains. Divinity, Space, Time, and Soul. The former as it involves direct tinkering with your own essence and nature, the last because it involves much the same for everybody else, and the middle pair because the dramatically weakened super-entities are still strong enough to impose limitations. These are the heftiest Domains for a reason. They also provide major benefits. Soul, for example, enhances many forms of empowerment and unlocks a lot of projects. Among other things.
Actions:
In theory, anything you want to do can be done, though you're going to want high Domains for anything like 'Make everybody Captain America without crazy dietary requirements or else their body cannibalizes itself.' You begin with 3 Actions, gaining an additional action with each magnitude your number of followers increases. 1->10 would move you up to 4 Actions. Note that gaining High Priests will also grant actions, but they tend to be literally one in a million, and there's no guarantee they'll follow you even if you find someone who is, in theory, compatible. This first one is a freebie, though you'd have to be a pretty nasty customer to lock one or both the others out.
At any rate, Faith can be used to generate more Actions as well, sacrificing 25% of your Faith income to grant an extra Action or increase Action number by 25%, whichever is greater. Until you hit 8 Actions(so, not any time soon) it's going to be 1 either way. This can be toggled for 50, 75, or even 100% if you wish.
Actions will default to 1d6 to the relevant task, with difficulty determined by me. Making your High Priest into Captain America is a base of 25, for example. This is relatively easy because it's one person. If you have Life, Evolution, and Enhancement at 1 apiece, it drops to 10, and you go from 1d6 to 4d6. Pretty much a guaranteed success if you get even average rolls.
It should be noted that Actions can be used for three main things. Making things, buffing people(temporarily via blessings, or permanently via Empowerments, though you'll need an empowerment method first, such as Qi, Magic, or Psi), and information-gathering, though all of these tend to require requisite Domains to be very effective, and followers tend to determine your area of influence. As of game start, you have a couple square miles around your High Priest available to mess around with. Doing Actions beyond this area tends to cause penalties to your dice at best, or outright fizzle out at worst. This is because, at least initially, your followers act to stabilize you. You are, as I said, essentially the energy being equivalent of a bunch of corpses sewn together. Some scarring makes sense, yes?
You can make artifacts, which essentially work on divine energy, and will, under normal circumstances, work pretty much forever unless actively destroyed. Relevant Domains influence overall quality, though this is mostly because of the imparted knowledge translating to improved skill. Then there's Marvels. Stuff like Excalibur, though it can also be more in line with the Philosopher's Stone. In theory you can grant every High Priest a Marvel, but you're never going to have the production to give every follower a Marvels once you hit triple digit followers.
Buffing people can be a general boost, or focused, though specific Domains will always help. Speed and Strength Domains will make buffing those things much more effective, for example. Empowerments are similarly effected. If you have Magic and Psi, Empowering followers will give them those, but not Qi.
Information-gathering is influenced by both knowledge-based Domains such as Learning and Knowledge, and Intrigue focused ones like Intrigue and Searching. Divination, Foresight, Hindsight, etc. are also viable means of gathering intel, though it should be noted that prophecies are usually fairly unreliable without major investment and/or a relevant Marvel. Not the least because the vast majority of the time you are a complicating factor even if you don't have anything in the Time Domain. You are both more constrained and freer than most beings.
Omake Policy:
Much like Actions, I'm going with a policy that Omakes have a baseline of either +25 Faith as of any number of Faith below 1000, from there, it doubles with every magnitude of increase, 50 as of the fourth digit, 100 as of the fifth, and so on. Quality and length can increase this. You will also have the option of directly investing in a Domain of your choice, or dumping it into the general pool. I should note that I love Negaverses and Crossovers(gee, who'd have thunk?) though obviously it's a little early for the former.