From the time he showed up until he was eaten by trolls, Gort of the Shining Force was a very amusing NPC to have in my game.
He was cast as a retired former adventuring hero with a lot of experience but badly deteriorated skills. But it was fun to have him blurt out all sorts of "Back in my days with the Shining Force" reminiscences that could potentially be useful. After all, he was a been-there, done-that, back-in-my-day type of guy.
So I added a new, one-character-only skill to his sheet:
Hidden Lore (Dungeoneering)
This skill covers oddball bits of knowledge and experience picked up by an extremely (but randomly) experienced delver. It involves little bits of monster lore, professional knowledge about how to coil rope, hammer in iron spikes properly for keeping doors open or closed, how to tap for pits properly with a 10' pole, what monsters might like to eat, how it was done back in the Palace of the Silver Princess or that time in Felltower, etc. If these are covered more specifically by another skill, roll against that instead - this is more like Jack-Of-All-Trades for dungeons.
On a successful roll, you know how to do the task at hand in a "proper delving fashion," or have some tidbit of possible useful knowledge. On a failure, you have a useless piece of information or have some not terribly helpful way of accomplishing the task.
Why not a Professional Skill?
Because it's not just knowledge about the ways and means of doing a specific job. It's a catch-all category of:
- dungeon lore
- professional knowledge
- monster lore
- everyman skills for dungeoneering
Is this a serious skill?
No, not really. It was an excuse to roll against a 10 or 11 or less and have Gort chime in with some information or be able to accomplish some "basic" delving task that is probably not that trivial (like, tap for secret doors, or spike doors open, or tie up prisoners). It was just a "Is Gort going to say something useful or useless?" roll.
I wouldn't allow a PC to take this. It's potentially too broad, and turns from "What does Gort know?" into "GM, tell me how to solve this problem." I hate those kind of rolls. I prefer people to come up with solutions themselves, and then use Knowledge skills to determine if the solution is a good one . . . not assume their guy has a hidden stock of GM-provided answers at hand. How to, not what do I know.
But "What does the NPC know?" is a really valid concept for the GM. So if there was another Gort-like NPC out there, I'd use this again.