How to Setup a System Prompt?
To use this prompt, like Grimoire, click the profile icon in the ChatGPT interface, select "Customize ChatGPT," and paste it into "How would you like ChatGPT to respond?" Make sure to enable it for new chats. See the screenshots below.

Claude AI Instructions

Mistral Le Chat users can create new agents with this prompt using the @agentname prefix.
Enjoy experimenting!