Game Store DM let his friend be Omnipotent
There's enough time that has lapsed during which I think I can post this.
I joined a local DnD group, very excited, with a friend. We were both excited to play a little extra on top of our other session, and the game was advertised as 'friendly to newcomers' -- Great, right?
When we arrived, we both had characters prepared, but we were also offered sheets. My friend took a sheet, I said my prepared was a sorcerer, and the overall vibe was a very enthusiastic 'yes please, we need a full-caster!'
We learn that it's mid-sesh, but the DM is fantastic, and our characters are both found tied up in a dungeon. (This is to say that the DM is doing well, I'll skip to the horror now.)
I can't remember exactly what we were playing, but every single time this teeth-smacking, lean-backing, 'uhm, actuhally' guy was playing the most obnoxious character. A cleric. Who had access to every spell. Literally ever; regardless of level.
This happened all the time. It was insufferable. If the other players (three others) attempted anything, this 'cleric' would have already dealt with it. I think it was because they had a library (why not Wizard?) to spin out crazy spells.
This guy would lean back in his chair, and rolled for nothing. He would ask the DM (his well-meaning friend) if he should just "finish it", because his character was so OP that he never rolled.
DM, granted, saw my absolute disgust via my in game challenges. As in this guy said "Yoink!" (verbally) to take something from me, and I snapped that he'd have to do a contested check. I won the check, and he was bitter.
DM said that they would be harsher on the guy's character creation in the future, but I can't imagine how bad it was for the other people involved for longer.
The DM also cut us off at the last sesh because "it was only fighting" because they wanted to move to their homebrew... Like. Fighting after you level up is half the fun!
This was over about 4 sessions.