Minecraft wiki entry for Trading, associated text: The main reason to have a cartographer is to obtain explorer maps for ocean monuments or woodland mansions, in addition to unique banner patterns. Paper is sufficient to level it up, but if you have lots of sand, glass panes work fine, too. Once you have purchased the maps, the villager is still relatively useful, as paper can be continuously sold to it, as long as the player's sugar cane farm productivity is high enough.