Additional Favored Class( Unearthed Arcana, p. 100)
You are more adept at combining different talents than most members of your race.
Choose a character class, such as ranger. The chosen class is treated as a favored class for the purpose of determining whether your character takes an experience point penalty for multiclassing.
You can gain this feat multiple times. Each time you take the feat, it applies to a new class.
Without this feat, if any class other than your race's favored class is two or more levels lower than your highest-level class, you take a -20% penalty to XP earned for each class that is not within one level of your highest-level class.