I'm creating a piece of Software that is designed to assist dungeon masters when playing Dungeons and Dragons 5th edition. I've been trying to determine who much information/text from the main rule book I'm allowed to incorporate in the software. I've done some digging around already and have found that game rules cannot be patented. However, there are many instances when the rules have very strict definitions and would require an almost verbatim copy from the rule book to the software which I'm concerned would violate copyright and constitute plagiarism. How are these types of situations interpreted and is there a litmus test I can apply to determine how to proceed with these situations?