A variant card is one of a certain number of promotional cards randomly included with Special Edition packs. Prior to recent times, they were of a high rarity, although their mass-produced status countered the usual tendency of those high-rarity cards of being considered particularly valuable. The early variant cards were Ultra Rares, with the later ones being Secret Rares.
In recent times, the cards have nearly always been of low rarity, the latest ones usually being Super Rares.