None of it from 5e, though. 5e is where demigods lose the ability to grant spells, so 5e is where you need to prove the promotion.
And for some reason the MM and Volo's declaring that he has cultists and answers prayers (things demigod can't do) and the cult fanatic with cleric spells who is designed for doing things like worshiping Yennoghu (but isn't specific to him since it is a general cult leader to slot into many different cults) isn't enough evidence for you because... you don't like it and therefore won't accept it.
Correct, but we have the PHB to prove otherwise about lesser and greater gods.
In general sure, but you can't prove that any given god has magical clerics in their church. You can only prove that a DM might include one, the exact same general use that the Cult Fanatic has, that you refuse to acknowledge.
I mean, you can show me a statted up 5e cleric of Celestian right? That's the exact same requirement of evidence you gave me, so that's fair, correct? Actually, I'll give you a better shot. Find me a statted out and officially printed cleric of Celestian, Ralishaz, Trithereon, Ulaa or Beory. That's five different gods/goddesses, so it should be even easier for you to find at least one officially statted up cleric for one of them, right?
I'm sorry. You presented evidence? I'd love to see it. So far all I've seen is your assumption that just because some cults have Cult Fanatics, that somehow proves that Yeenoghu must have them as well.
Cult Fanatics are literally listed as cult leaders for Demonic Cults. Yeenoghu has demonic cults, and we are specifically told that humans can rise through his cults to lead them. Even getting additional magic powers if you want to use the rules in Mordenkainen's, which actually directly states "Cult Leaders gain the Aura of Bloodthirst trait" which is supposed to apply to a non-gnoll. And, we have a statblock for a cult leader, the Cult Fanatic, which directly says " Fanatics are
often part of a cult's leadership, using their charisma and dogma to influence and prey on those of weak will."
So, yes, I can't think of any reason to dispute this, except you don't like it.
Let's look at the Greyhawk wiki, since wikis are entirely accurate according to you.
First, your claim of 70 years of rule and indoctrination is bupkis. He took over in 479 and by 505 he had been defeated by a wizard and imprisoned under Castle Greyhawk. Some poweful god being he was to be taken out by a wizard. Anyway, that's 26 years and then the country gets to see just how weak he was. His followers split at that time. He comes back in 570, sixty-five years later. That's 65 years without this indoctrination. This time he lasts a mere 11 years before Vecna, who was only a lich at that time captured and then consumed Iuz, using him to become a real god(liches know how to do it!). That only lasted a year, though and he returned in 582. In 586 half his army was wiped out when many fiends were banished from Oerth. Now we're caught up in time and he has a broken rule in which he is repeatedly shown to be weak, and most of the 103 years since he appeared in that country have been spent by him imprisoned or dead.
Iuz is the half-fiend or cambion demigod son of Graz'zt, a demon lord of the Abyss, and the human witch Iggwilv. Originally described as very handsome, Iuz now appears either as an old man with poisonous spit, or a big, red, hulking demon-like creature. His weapon of choice is the whip and...
greyhawk.fandom.com
Which proves you don't actually read the evidence. To quote directly from your own link: "In 505 CY Iuz vanished.
Many of the orcs, clans that had served him for years, as well as some of his human followers claimed he has ascended to full godhood, beginning to worship him, and actually able to perform cleric spells based on their worship."
What's that? Real worship that led to clerical spells? I thought you said almost no one really worshiped him? Additionally, he was a demigod by this point in time, since if we follow the link to Zagyg it says "In 505 CY, Zagyg succeeded in capturing nine demigods of opposing alignments and imprisoning them beneath Castle Greyhawk.". So, in 26 years he was already a demigod, since that was when he was captured, and his worship only
increased after that point.
Also, if we count this time of his people saying he ascended to full godhood and were actively worshiping him (because they didn't know he was captured) what do we find? Well, he was captured for 65 years, like you said, and what do you get if you add 26+65? 91. So, about 90 years. Like I kept saying. So, while imprisoned, the apparatus he had put in place, led to his continued worship and the indoctrination of the populace. Again, like I kept saying.
As I just proved to you in the quote, there are quasi-deities on that list who are incapable of granting spells. Perhaps their priests get spells from the god they serve. Perhaps it's up to individual DMs to promote them. But we have this absolute fact. 1) despite every god on that list being called a god and having domains, some of those gods are in fact demigods who cannot grant spells. I'll quote it again in case you missed it.
"Choose a god, a pantheon of gods, or some other quasi-divine being from among those listed in appendix B or those specified by your DM, and work with your DM to detail the nature of your religious service. Were you a lesser functionary in a temple, raised from childhood to assist the priests in the sacred rites? Or were you a high priest who suddenly experienced a call to serve your god in a different way? Perhaps you were the leader of a small cult outside of any established temple structure, or even an occult group that served a fiendish master that you now deny."
So, you are convinced that that refers to beings that no one would have any idea were demigods, and not to the ones like "The Blood of Vol: Philosophy of immortality and undeath", "The Path of Light: The Philosophy of Light and Self-improvement", "The Undying Court, Elven Ancestors", and "The Spirits of the Past, Elven Ancestors" the only things in appendix B NOT called gods, and which would be quasi-divine beings, such as vestiges.
Also, this is again for the Acolyte background, just to be clear.
Tempus probably does it, since she's his Exarch.
So, Tempus hears the prayer, sends it to the The Red Knight, who then takes it to Tempus, and then tells her to grant the prayer with magic, that Tempus then provides and uses to grant the prayer... seems like an utter waste of everyone's time if Tempus is just going to do all the work anyways.