The Seals of Cthulhu

From BoardGameGeek:

A quick-playing yet very strategic bidding and bluffing card game, set within a Cthulian universe, where 2 players battle for the fate of the world. One player assumes the role of a cultist, bent on bringing about the end of the world. The other an investigator seeking to thwart the cultist and save the world. Players use the forces under their control to try and gain artifact cards, seeking to complete them and unlock powerful abilities. These artifacts also allow players to gain control of other cards...at the sacrifice of giving them to their opponent. You must outwit and out-strategize your opponent if you hope to win the battle. -description from the publisher