The Invader series of Doctor Who: Battles in Time trading cards was the second expansion series to the original set and followed the success of the previous sets (namely Exterminator and Annihilator). It was launched in September 2007 with a special card-mounted magazine issue which included four packs of trading cards. Additional packs were also available for purchase separately. The Invader series consisted of; The much sought after, gold ticket card (of Rose Tyler possessed by the Time Vortex) remained available in every thousand packs and was a thicker, gold foiled and unnumbered card.