Mordenkainen Presents: Monsters Of The Multiverse

If you haven’t already taken my advice and jumped ship from stock 5e Dungeons & Dragons to Advanced 5th Edition, here’s another book with which to consider augmenting the core rules.
If the core of Dungeons & Dragons is the combination of the Player’s Handbook, the Monster Manual, and the Dungeon Master’s Guide, then Monsters of the Multiverse begs to earn a spot as the fourth core book (competing, maybe, with 2020’s Tasha’s Cauldron of Everything).
You’ll get a ton of fun, unique monsters to throw at players, but you’ll also get some new Race options, and this is where I think Monsters of the Multiverse really earns its place. It contains the more flexible and much better race rules from Tasha’s Cauldron Of Everything, where stat boosts aren’t based on essentializing qualities, but can be chosen by the player. It also adds so many more options for fun characters that the Player’s Handbook looks like a mere playtest of suggestions.
It’s a solid D&D book, and a great resource for both Dungeon Masters and players. You can also get it in a gift set with two other books that have refreshed 5e’s rules, Tasha’s Cauldron of Everything and Xanthar’s Guide to Everything. If you’ve been mostly using the core rules for all these years, these three are the equivalent of a huge DLC drop of new rules, character options, classes, and monsters.