Battlegrounds is a real-time adaptation of Magic: The Gathering. Players build 10-card decks out of a selection of about 60 cards; cards are real magic cards, but some are modified slightly for balance.
When a duel begins, each player only starts with 1 mana crystal. Mana crystals gradually appear as the duel goes on (more slowly the longer the duel lasts), giving you access to more expensive spells. Duelists can summon creatures that attack enemy creatures or duelists, cast enchantments to give a global effect, or cast spells to cause various effects such as buffing their creatures. The duelist can also perform a weak melee attack that deals 1 damage to a nearby creature.
As in the card game, players start with 20 life, and lose when their life is reduces to 0. Decks can consist of 1 or 2 of the 5 Magic colors.