As revealed in an advertisement in the trade publication ICv2 and later confirmed by Mark Rosewater in his column, Morningtide expands upon Lorwyn flavor and theme by focusing on at least five classes (Soldiers, Shamans, Wizards, Warriors, and Rogues) as well as a few minor class-based tribes (Druids, Archers, Knights, Clerics, and Assassins) in addition to the eight races of Lorwyn (Kithkin, Merfolk, Faeries, Elementals [Flamekin and Greater], Goblins, Giants, Treefolk, and Elves). Additionally, three new mechanics got keyworded with this expansion, namely; Prowl, Reinforce, and Kinship.
Four preconstructed theme decks have been released as part of the set. The theme decks are "Battalion" (White/Blue), "Going Rogue" (Blue/Black), "Shamanism" (White/Black/Green), and "Warrior's Code" (Red/Green).