The Denethor cards are an 8 strength, 3 vitality companion for only 2 cost because most of them have a negative effect as well. It plays off the concept in the books and movies that Denethor was a troubled mind.
Of course, in the books he was an active commander of Gondor during the Siege of Minas Tirith until he saw his wounded son and looked into the Palantir--that's when he went crazy. In the movies, he was just a malcontent psycho.
-wtk