Bill Zebub
“It’s probably Matt Mercer’s fault.”
Wow, the visceral reaction I had to that sentence.
Well, let me clarify:
1) There is a lot about GMing that is unique to the hobby about which LLMs may not know anything. Then again, there is a lot of text information out there about the hobby including examples of play and guidance for GMs, so it might.
2) Then there's just basic storytelling skill. So far I'm blown away by how creative ChatGPT has been. It would not surprise me in the least if it were able to give me feedback on my storytelling skills.
I wouldn't recommend judging what it can or cannot do before exploring this personally.

