Is "The GM's Book of Legendary Dragons" a valid D&D 5e rulebook?

Question

True to the holiday season, I recently received an RPG rulebook titled "The Game Master's Book of Legendary Dragons."

At first glance, there was no doubt in my mind that it was meant to be a D&D 5e rulebook. It has spells unique to fifth edition, a foreword by Luke Gygax, and formatting for the dragon stat blocks in an identical manner to the beloved Monster Manual.

However, on closer examination, some red flags seemed to appear. Notice that the title says 'Game Master' instead of 'Dungeon Master,' as the DMG does. It also doesn't say 'for D&D 5e' on the cover, but 'for 5th edition RPG adventures' instead.

So is "The GM's Guide to Legendary Dragons" a valid D&D 5e rulebook, or merely an off-brand supplement?

Answer 1

This is not from Wizards of the Coast, nor is it an official rulebook

The publisher of this work is Media Lab Books, a MacMillan Publishers subsidiary, also using the name "Topix Media Lab".

You can see indications that this is not a licensed work from the fact that the title uses the term "Game Master" instead of "Dungeon Master", and "5th Edition RPG" not "Dungeons & Dragons 5th Edition" – because both terms "Dungeon Master" and "Dungeons & Dragons" are Product Identity owned by Wizards of the Coast, and would require a license. The Open Gaming License, or OGL, states (emphasis mine):

The following items are designated Product Identity, as defined in Section 1(e) of the Open Game License Version 1.0a, and are subject to the conditions set forth in Section 7 of the OGL, and are not Open Content: Dungeons & Dragons, D&D, Player’s Handbook, Dungeon Master, Monster Manual, d20 System, Wizards of the Coast

However, that does not mean it is "invalid", only that it is not officially endorsed. Third party publishers have the right to publish works under the Open Gaming License. Even while this is not an official WotC product, it is part of a series that has relatively high sales ranks on Amazon for D&D, so it seems to be quite popular with many players.

Answer 2

This book is published by Topix Media Lab

This is a third party supplement licensed under the Open Gaming License for use with D&D 5e, published by Topix Media Lab. It is not an "official" supplement, that is, it is not published by Wizards of the Coast.

That said, James Haeck and Dan Dillon have both worked as writers on many official sourcebooks, so seeing their names on a third party sourcebook should at least tell you that this isn't just some random fan's shoddy homebrew.