Lord Vatticus is a NPC Trader that spawns anywhere in the Dungeon of Arcana. It has 1000 Health, and will not be provoked if attacked. You can trade with him to get various types of armor, as well as some other equipment. Lord Vatticus is responsible for getting you 2 Achievements: "Enrichment" and "Yuk!".
Finding Lord Vatticus
Lord Vatticus is not particularly difficult to find, as they spawn all over the Dungeon of Arcana. However, they spawn more often in open spaces, so it is best to look for them there.