This is another in the series of "wanted" posters that can be found within a campaign setting.
-As implied by his name and dress, he is a mage of some type. What type could change the parameters of the adventure. Of particular interest is that he is only wanted for questioning. Apparently, he is not the sort of person who willingly will go in for this "questioning", otherwise there would be no need for such a poster. Perhaps he is a recluse or is hidden or too powerful for conventional forces to apply pressure on him. The challenge for such an adventure consists of first finding him and then convincing him to come along. If he is too powerful for the party to convince through strength and combat, he may be willing to accompany them...after they first complete a seperate adventure for him first.
-This is a straighforward opportunity to move the party from one location to another. Of note is the fact the poster specifes experienced fighters and casters; this implies the people who posted the item are expecting trouble. If the players are eager and willing to pursue this opportunity it may be a way of letting the DM know they feel their current area of adventure is overused or holds not enough of their interest.