From UO Excelsior Wiki - Ultima Online Free Shard
When a non-Champion/Named Monster spawns in Ilshenar, there is about a 5% chance it will be a Paragon of it's kind. Paragons are far more powerful then a standard creature of their type, and the stronger examples can potentially kill an unprepared player within a couple of seconds.
Defeating a paragon provides a chance of having a Traditional Minor appear directly in your pack dependent on the Fame of the creature, and your level of Luck. Although they don't give artifacts terribly often, the paragons themselves are fairly easy to locate (and often to defeat) and so their specific artifacts are considered common.
Paragon creatures capable of dropping Treasure Maps as loot have a 10% chance of providing a special chest on death. This chest contains a map that is one level above whatever that creature would usually drop. Ingeniously drawn (Level 6) maps are obtainable via the chests dropped by monsters who would normally drop Devious (Level 5) maps.