Battlecards are one use battledome items you can win from Cheat!.
Battlecards come in three different varieties: regular cards, which are recognisable by their red borders, silver and gold. Generally speaking, gold battlecards inflict more damage than silver cards, and silver cards do more harm than red ones. The degree of damage done also depends on who is depicted on the card; the better the Cheat! player shown on the card, the greater the damage inflicted. For example, a battlecard of Spectre the Jetsam is likely to hurt your opponent much more than a card of Capara the Kyrii or Branston the Eyrie.