Boss Monsters are encountered in all Fate games. They are usually found for quests, but are sometimes encountered randomly in the dungeon. They can also be encountered on all levels.
Boss monsters are notably different in appearance from their regular monster counterparts. They have a distinct red glow below them, and are larger then regular monsters. They appear only in levels where normal monsters of their type would appear. For instance, a Dire Walrus of any type will never appear as a boss monster in in the Druantia realm, where they never normally appear. They always are named, and are not simply named their monster type, like "goblin". They often have resistances to certain weapon or magic types. They are leveled, so a dragon boss will never appear on level 2, for instance. When killed, they often drop large sums of gold, and enchanted weapons.