Eternal is a turn-based card game between two opponents that use constructed decks with various amounts of cards. Players use their power cards to cast spells, use attachments or summon units to attack the opponent, with the goal of reducing the opponent's health to zero. Winning matches and completing quests will earn in-game gold, rewards in the form of new cards or packs, and other in-game prizes. Players can buy card packs or access to card drafting modes by using gold or real money microtransactions to collect cards for use in their decks. There are also cosmetic items for purchase. The game features several modes of play, including ranked matches and single-player campaigns. New content for the game involves the addition of new card sets and gameplay, taking the form of either expansion packs or campaigns that reward the player with collectible cards upon completion.