The friends and foes of Eberron and all its planescape neighbors is a neverending list, constantly lengthened and further detailed by explorers, researchers, and adventurers.
These entries are directly influenced by your level of observation, with the following rules.
Sighting a creature will earn you a depiction of the creature, either visual or verbal. (Level One)
Fighting a creature will earn you details of its physical attributes. (Level Two)
Repeated combat with a creature, or researching it to the appropriate extent will earn you the Dungeon Master's entry on the creature, including lore and abilities, which may disclose weaknesses and strengths in combat. (Level Three)