This expansion for Magic: The Gathering takes place on Kaldheim, an icy world (or rather, cluster of ten worlds) inspired by Norse Mythology. Kaldheim consists of ten realms: Bretagard, home of the human clans; Istfell, home to the spirits of the dead; Karfell, home of the undead draugr; Immersturm, home of the demonic hordes; Gnottvold, home of the trolls; Starnheim, home of the valkyries; Surtland, home of the giants; Skemfar, home of the elves; Axgard, home of the dwarves; and Littjara, home of shapeshifters.
New mechanics in the set include foretell, which allows spells to be placed on layaway for later, and boast, which allows creatures to activate a special ability on any turn where they attack. Also included are several returning mechanics: modal double-faced cards (originally introduced in Zendikar Rising), changeling (originally introduced in Lorwyn), sagas (originally introduced in Dominaria), snow-covered lands (originally introduced in Ice Age), and snow mana (originally introduced in Coldsnap).
The set is sold in draft boosters, set boosters, collector boosters, theme boosters, and bundles, and it contains 285 cards (121 commons, 80 uncommons, 64 rares, 20 mythic rares, and 10 snow-covered basic lands). An additional 15 uncommons and 5 rares are found only in set boosters and theme boosters. The main set is also accompanied by two preconstructed commander decks that tie into its themes.