It goes without saying that there are a lot of books in the D&D library. Take one look at the product list on something like D&D Beyond and you'll see that the shelves are practically breaking under all of those adventures and supplements. However, I'll always argue that three are more important than any others.
Assuming you have the core set already (the Player's Handbook, Monster Manual, and Dungeon Master's Guide), I would say the most helpful expansions are contained within the Rules Expansion Gift Set... which just so happens to be half price at Amazon right now. While this three-pack is more for Dungeon Masters than anything else, it's crammed with info useful to players and DMs both - including bonus character or class options, advice on making good puzzles, and a wealth of new playable races to try out.
I've sketched out details for this add-on to one of the best tabletop RPGs below.
Should you buy the D&D Rules Expansion Gift Set?
So, why is this D&D bundle worth bothering with? For starters, I'd say it's a solid way of taking your games to the next level regardless of whether you sit in front of or behind the DM screen. Both Xanathar's Guide and Tasha's Cauldron provide loads of new character options (not to mention subclasses), and the latter is your only way of getting the D&D Artificer class. What's more, they go into great detail on how to improve campaigns or make your own realms with insightful tips. I've been playing D&D for a while (I wrote our Tasha's Cauldron of Everything review, actually), and these have been some of the most inspiring to me.
Monsters of the Multiverse is equally good. Besides giving Dungeon Masters more enemies than they'll know what to do with, it features all of the playable races that were scattered across various Dungeons and Dragons books. They've also been rewritten to fit any setting, rather than the more prescriptive settings they used to have.
Crucially, all of these will still be valid when the next edition of D&D arrives. While the core rules are being superseded, the game's developers have promised that these should carry over. That means you won't feel short-changed by the prospect of imminent replacements.
For more recommendations, be sure to check out the best board games and the best card games.
