Like its predecessors Theros Beyond Death has an ancient Greek themed top-down design, making use of many mythological tropes (Heroes, Monsters, and Gods).
The main set contains 254 cards (5 basic lands, 101 commons, 80 uncommons, 53 rares, 15 mythic rares), and includes randomly inserted premium versions of all cards. Additional cards are found in the set's Theme Boosters and planeswalker decks. A unique Buy-a-Box promotional card is also considered to be part of the set. Cards with alternate card frames have another card number than the original version. Borderless planeswalkers are numbered #255-257, Showcase cards are numbered #258-268, the Buy-a-Box is #269, planeswalker deck cards are numbered #270-277, non-constellation basic lands are numbered #278-287, Theme Booster rares are #288-297 and extended artwork cards are numbered #298-351. The Bundle promo is numbered #352. Finally there are FNM-treatment cards from the Universal promo pack numbered #353-357. Both regular and foil versions of these cards may be found in the collector boosters.
The set features five special Nyx-inspired full-art constellation basic lands (one per pack). The non-constellation basic lands are only found in supplemental products. These regular-border lands depict the "Above and Below" of Theros and its underworld. Besides the five basic lands, there are 11 constellation showcase cards. These are all the gods and demigods.
The set's expansion symbol is a Mask of the Returned.