A "magic barrier" is a mechanic used by the spells Energy Barrier and Mana Pylon, both from the Mage's Mana Control discipline. This is not to be confused with Conjurer's Life spell Magic Barrier, which simple reduces the magical damage received by an ally. Energy Barrier can be recasted while still active and thus it regains total power, but never stacks. If a player had 500 barrier left and casted Energy Barrier (5) he would have a total of 1000.