The Theros Beyond Death Deck Builder's Toolkit is a box set that was released on January 24, 2020. It contains 100 basic land cards, 125 fixed cards suitable for improving the Planeswalker decks, and four 15-card booster packs (War of the Spark, Core Set 2020, Throne of Eldraine, and Theros Beyond Death). You also get a deck builder's guide with tips about building the best Magic decks, a Magic "learn to play" guide and a full-art reusable card storage box.
Like most recent versions of the Deck Builder's Toolkit, all the cards in this product (except for the cards in the boosters) are entirely fixed, providing R&D full control over the experience and allowing them to plan out the deckbuilding options that players will find when looking to upgrade their Planeswalker Decks.
Each toolkit contains 125 fixed cards (in addition to 100 basic lands).
1 So Tiny