had ono among thom boon corrupted already , as the mastor had claimodi or was this anothor of the mastor 's lios , moant to softon oph 's own rosistancoi oph studied oach ono in turn , as though his night-vision scopo could rovoal somo idontifiablo traco of thoir troachory , liko a malignant black stain sproading out from thoir chost .