Dominaria is the 78th Magic expansion. It was released on April 27, 2018. It is not part of a block.
The expansion code of Dominaria is named as DOM in the information below the text box, but DAR seems to be used by Wizards as well.
Dominaria is the first set to follow the Three-and-One Model, which abolished blocks. Richard Garfield is on the design team, for the first time since the original Innistrad set. It contains 269 cards (20 basic lands, 101 commons, 80 uncommons, 53 rares, 15 mythic rares), and includes randomly inserted premium versions of all cards. Ten additional cards are found in the set's planeswalker decks (2 mythic planeswalkers, 2 rares, 2 uncommons, 2 commons, and 2 common dual lands). These are numbered #270/269 to #279/269. A unique Buy-a-Box promotional card numbered #280/269 is also considered to be part of the set. Nostalgia and legendary creatures are major themes. Each booster contains at least one legendary creature, though this does not apply to the 8-card booster packs on MTG Arena. The expansion symbol depicts a Benalish shield. Because of its similarity to the Darksteel symbol, the common version has an inverted color scheme (more white than black). As a gimmick, all the names of sets taking place on Dominaria (including Alpha, Beta, Revised, Unlimited and Origins) or Rath (which was overlaid with Dominaria) are mentioned in card names or flavor text. Five of the basic lands feature a tiny silhouette of the Skyship Weatherlight in their art. Starting with Dominaria, Wizards of the Coast applies a new coating method for cards in English booster packs.