Not This Guy. He'll happily have his DMPC wipe an encounter by himself. He had a side story all about how this DMPC is destined to destroy an ancient immortal Prismatic Dragon.
This is the bad DM/Problem Player I've been complaining about again, and again, and again, and etc.
Seriously though, he'll ban stuff, but still use it for himself. Or without actually checking if it is as broken as he claims.
The only player who is truly overpowered, other than the DMPC, is the Ranger/Paladin. The only other characters that can clear an entire room by themselves are the DMPC and the Wizard/Arcanist if he gets good damage rolls on his Fireball.
Most i had for a DMPC was the party's first NPC ally who eventually became guildmaster of the local thieves' guild. It was obvious he was getting absurd amounts of wealth because after some sidetracking, he returned to the party with a lot of magical gear, and went from wearing basic leather armor and common clothes to the best he can possibly get as a 5e rogue and elegant travel clothes.
He was gonna be the surprise final boss for the entire game, where the party follows leads on my world's equivalent of Jack the Ripper (or joker, your pick) who mass murders people (he took out the entire night crew of guards tailing a fellow criminal who's a PC) and steals the souls of people and feeds the soul gems to a demon lord who gave him immortality and power since hes a warlock. When the party finally found out he was the town sheriff, because he killed the real one and stole his identity (they had the same name, and the biggest thing about it, is that the sheriff was supposed to be alive for the majority of the time there while the DMPC took over.
One of the things that lead the party to investigate the sheriff would be the body of someone resembling the sheriff who was mutilated, and by then, the party had obtained two soulstones (one of a party member, the other of the sheriff, both would be unknown until this point) and then it would make sense by the soulstone being near the body as the spirit was finally set free, telling the party he was the real sheriff, and that the one there is an imposter.
The party would then hav to figure out how to get into the guild and start a rather linear but VERY VERY rewarding questline into the underground network of the city, killing/apprehending the fences, the contacts, and so on, until they make it to the guildhouse itself, where they would, not only find several loved NPCs they liked there, but alternate characters that they made and swapped to (which was a big mistake on my end). They would also make it to what looked like the seat of the guildmaster with the warlock on a throne of sorts, surrounded by gold and soul gems. He would then battle the party after dragging them into the abyss, and then after they slay him in normal form, he would rise up again as a half demon, and then the party would not end up killing him, but rather watch him get pulled into the abyss by the damned once defeated.
When that ended, the party would then head out of the empty guild hall, with three people stopping them from leaving: the guildmaster, the head fence who was the party's beloved merchant of everything but what she advertised (she was a shoemaker who had everything but shoes in stock), and the resident badass who was the mercenary muscle of the guild AND the head of the underground pugilist's guild. The party could only turn the merc over down, but only one character could do it, the fence would fight the party regardless due to her friends (the fences and guild member PCs) being slain/apprehended, and the guildmaster himself would battle because he knows that since he's the leader, he has to fight, as reluctant as he would be to fight his closest friends and companions.
The fight was to play out very chaotically, with the fence pulling out her signature weapon, a portable ballista, the guildmaster using two blades that he had custom made for himself, and the pugilist leader using the full extent of being a Way of the Four Elements monk.
Once the party completed this quest, the city they were in would start to go into anarchy, and, if the party killed everyone, the guild is erased, but the town's sources of income and such are brought to such a low that everyone would become poor, and the city would just collapse. If the party killed most (70% or more) of the guild, the city's economy would drop, but the remaining guild members would try to stabilize the economy back to primarily using adventurers to buy and sell gear, providing new adventurers with things, etc, and people would still come. If the party left 70% or more alive, the guild reforms, but doesn't go as extreme and expansionist as it did before, and the econcomy of the town is still stable. Sparing everyone save the hitman would end up having the guild return but the guildmaster would eventually turn the guild's profits into forming his own town, which was an entire city based on commerce.
I wanted to do this and bring it to fruition, but I would either get salty players or one of the most heart wrenching games I ever played