@JeremyECrawford is the Explorer's Guide to Wildemount considered official D&D material? Certainly Mr. Mercer is an expert weaver of tales and is very familiar with the mechanics but are these subclasses, items, and spells tested? Has it gone through what other books go through?
— DrewFlashy Pokemon Shield (@DrewFlashy1) January 13, 2020
EXPLORER'S GUIDE TO WILDEMOUNT is a delightful introduction to the world of @CriticalRole. Like every D&D book, its rules have been tested by players, developed by the D&D team, and vetted by me. There are juicy subclasses, spells, magic items, and monsters awaiting you! #DnD https://t.co/by9s5P8tK9
— Jeremy Crawford (@JeremyECrawford) January 14, 2020
Is there a history of untested content being hardbound in 5e I should look out for?
There are, as occurred with some earlier editions (3.0/3.5), some open-license books published by private persons when/where there can be some question of how well the context was playtested or not. (Ex: Mercer’s first campaign book, Tal’Dorei, is pretty solid as a book *but* does have a couple or few instances of contextually “under-tested” material that he later retconned — a couple aspects of The Cobalt Monk sub-class, for example — and that’s an example of a “hardbound 5E book” that was perhaps under-tested. The official-by-WotC books, however, are generally well-tested; parts that later turn out to not work quite so well or need revision are errata’d and corrected in later reprintings and available for free at their website. Those corrections, though, are relatively few compared to the overall size of the material in question.) So it boils down to: if it’s official from WotC, then it should be reasonably dependable; if it’s open-license material, then buyer should beware/ask around for opinions from others first.