As a proper bug report. This should either be fixed or the description of Unarmored Defense/Mage Armor should be updated.
Title:
Mage Armor does not change base armor for Barbarians
Description:
Karlach was able to use a Mage Armor scroll that was acquired and has the buff applied to her character sheet, but the base armor remains at base 10 instead of base 13. By definition of Mage Armor and Unarmored Defense, Karlach should be able to use Mage Armor in conjunction with Unarmored Defense.
Wrong.
Unarmored Defense is by definition, an ability that only works with no armor. Mage ARMOR, as the title suggests, is magical armor, and does not stack.
