We first encounter Prolix in Asterix in the Soothsayer. He later also appears in the Anniversary album and he’s the protagonist in the movie Operation Getafix.

We are still not sure wether he can or cannot see into the future. 

In French and English, he is Prolix, referring to his “prolixity” or verbose way of speaking to deceive the villagers with word salad. In Dutch he is Xynix (zie niks), mocking that he “sees nothing” of the future, while the German Lügnix (lüg nichts) ironically commands him to “tell no lies” since he speaks nothing but falsehoods.