Books like The Unreasoning Mask

It is capable of alaraf drive: instantaneous travel between two points of space. Three of these special ships were built to explore and make contact with the many sentient races inhabiting the universe. Suddenly, one of the ships mysteriously disappears. And then it is discovered that an unidentifiable creature is marauding through the universe, totally annihilating intelligent life on planet after planet. Ramstan, a thoughtful and moral man, becomes a fascinated yet reluctant pawn in the hands of the strange forces which arise to fight the deadly destroyer. Ultimately, he is the one man who, in a fearful race against time, can stop the destruction. But what price must he pay for becoming the savior of intelligent-kind? The Unreasoning Mask is Farmer at his best: fast-paced, complex, slightly mystical, high-action adventure.