I was part of a long-running group with 3 rotating DMs (I was one of them) running a single campaign world.* We ran several different groups of various levels through the setting, from newbies to high-level.
One of the other DMs was running an adventure for the high-level group, and we just got stuck at this incredibly dangerous magical staircase because we couldn’t find a way down. After trying
for over an hour, we called the session for the night.
The DM was visibly annoyed at what happened and we were still mystified. As we were sitting there, finishing off our snacks & drinks, one guy just asked the DM point-blank what the solution was. He answered that we should have cast a particular spell, which would have completely neutralized the danger for a time. We looked at him kind of stunned.
“None of our PCs have that spell.”
There was some back & forth with him insisting that
someone did, and us protesting. He even looked at our character sheets to see if we were simply misreading them. He didn’t find it.
Then, mystified, he looked at HIS highest level spellcaster. There was the spell. In fact, that character was the ONLY character in the campaign who knew it.
And the groundwork for this fiasco had been laid down
years before. He played wizards
extremely well. He had independently figured out a near perfect powergamer’s spell list. And he only cast spells when they were necessary, so he was rarely tapped out.
He was also somewhat stereotypical in playing their attitude:
his wizards didn’t share anything magical. They grabbed up the best magic items suited for spellcasters they could; they
didn’t share spells for transcription into multiple PCs’ spellbooks.
IOW, if one of his wizards got a tome or scroll, any unique spell was going into his character’s spellbook ONLY.
I will also note that he
never changed this attitude. A few years after the events detailed above, we were both part of
another game group that lasted over a decade. When we went through RttToEE, my first character** (a multiclassed Diviner) was the second most powerful wizard in the party after his. And because of his speciality, he didn’t have many offensive spells. I suggested we transcribed spells from each other’s spellbooks, essentially making them “backups” for each other’s while increasing overall flexibility and punch.
“You don’t have any spells I need. So no.”
* DMs PCs would not be part of the party of any adventure the DM was running; only used as NPCs.
** I retired him to fill the healer gap when 2 other players moved out of town