Though I wanted to ask about the magical catastrophe that occurred in the past of your setting.
The Iconoclasm. Not to be confused with the real world Iconoclasm, which was a completely different thing over a completely different issue.
That's deep deep lore of the setting.
You mentioned it before and with the info you gave prior in this thread about clerics with knowledge based domains suppressing dangerous knowledge. Is the magic the ancient wizards used that caused the disaster part of the suppressed knowledge?
So, way back in the pre-history of the setting, their were four families of deities. They mostly got along and they dallied as deities do and made a bunch of children with each other. Then at some point the youngest but most numerous of the families had an internal feud that ended up creating all sorts of evils and horrors and getting gods actually killed, and that quickly spilled off into the God's War. The gods eventually decided on a truce to avoid spilling more immortal blood and to avoid wrecking the universe completely. During this mess, the last three families of deities were born (in what many suggest was an untimely premature fashion). After the truce, they were sitting around figuring out how to put the world back together, and arguing over the fact that none of them trusted the other ones to go back into the world for fear they'd set up fortresses their and claim it, and various other things beyond mortal ken, when Maglubiyet the Flame Eyed god put forth the idea that they should create servants, fashioned after the 'least gods' or fairies, to perform their will in the world and serve as their proxies. This led to more arguments over what exact form those servants should take, which ultimately led to a compromise that each family leader could submit their own design but with the caveat that each design should be free to choose which ever deity it wanted to serve and in its own way.
Thus came the six free peoples to join the seventh older race of fairy.
The children of Uman who had started the feud, still mourning their father and mother and the greater losses, submitted their design late and in the most desultory of fashions.
After a bunch of other events not pertinent to the story, the children of Uman finally sort of woke up and started paying attention to their hitherto largely neglected construct - the humans. During this period, the humans were a bunch of savage sorts, mostly living in caves, and generally not thriving very much except when they were serving one of the other groups. Deciding to rectify the situation, the gods decided to start tutoring their charges to see what they could learn.
The result would terrify the gods forever, for reasons that go into the deep dark lore of the campaign. The humans proved to be prodigious learners - vastly more prodigious than their creators had ever intended. Although none of the gods talk about it, all the deities had long observed that their was something wrong with their creations - namely they were able to grow vastly more powerful than they should have been able to. All their other servants had a fixed nature. A deity couldn't create a servant without pouring a bit of their native power into it, which would lessen their own power. The gods each pour a little bit of themselves into the mixture, but they hadn't poured much power into their new creation at all. The result should have been a minor servitor race with not much power. But that's not what had happened. The new mortals could demonstrably vastly exceed the power that had been given them with no apparent limit. The deities were already freaked out about that. Some thought that maybe one of the other deities had sabotaged the whole thing. Some thought they had discovered some sort of secret that would tip the war in their favor if they could just recreate it with a more useful servant. Some thought something scarier had happened. Nobody was absolutely sure what had happened, but when the makers of the humans started tinkering with their hitherto little loved creation, they found that the otherwise unremarkable race with no well thought out gifts could explode with power. Several of the deities started trying to see just how much they could learn. The result was 'The Age of Wonders', when humanity started to master magic to the point that literally everything that they did was magical. The 'Art Mages' as these group of wonder workers came to be called refined every skill to the point that if a potter cast a pot, or blew a glass vessel, or smithed a tool or implement, the result was magic. Bakers baked magic. Singers sung magic. Dancers danced magic.
The humans decided that they were the new gods, and decided further they didn't want to be ruled by the old gods. They went to war. And, on a lesser scale, it was basically the 'God's War' all over again. Things got wrecked. The humans launched assaults on Heaven and Hell. The gods retaliated. Eventually, when it became clear that they couldn't win, the humans started trying to create 'doomsday' weapons and threatened to blackmail the gods. Apparently the humans set one of them off, and to prevent it destroying the world, the gods for the last time acted jointly to rip a whole continent off of the planet and throw into the astral plane. The thing went off, wrecked the continent, but didn't spread. The mortal survivors of that wreckage founded what would more or less be the present races and political order, and the deities set out to make sure that no mortal would ever again spread knowledge that would be a threat to the gods themselves.
Meanwhile, the wiser gods are pondering what all of this could mean.
And with Karophet is that knowledge something that deity tries to spread?
Karophet is basically the god of technology, although certainly not the only one that could claim that title. Good aligned people would describe him as the god of knowledge and craft turned to evil purposes. He's the god of secrets, traps, weapons, engines, and forbidden knowledge. As such, yes, if you wanted to learn how to practice 'Art Magic', he'd be the guy you'd want to bargain with. The thing is Karophet is Lawful Evil. He doesn't want to destroy everything, he wants to rule it. And he's only going to risk the ire of the other gods if he thinks he can win. And further, he's not going to break the letter of any truce with other deities - even if he has no problem violating the spirit of the agreement when it suits him. And mortal that tried to bargain with Karophet would quickly learn why you don't enter into a bargain with fiends.