Increases your resistance to all magic by X and allows 50% of your mana regeneration to continue while casting. Only one type of Armor spell can be active on the Mage at any time. Lasts 30 min.
Increases your resistance to all magic by X and allows 50% of your mana regeneration to continue while casting. Only one type of Armor spell can be active on the Mage at any time. Lasts 30 min.
Mage Armor is a self-only buff that improves your resistance to all magical schools and allows you to regenerate your mana at 50% your normal regeneration rate when casting. (Without this spell, you do not regenerate mana for 5 seconds after completing any spell. See Five second rule.) Lasts 30 min.
In addition, the duration of all harmful Magic effects used against you is reduced by 50% when Mage Armor is Rank 5 (Level 71) or greater.
This is very handy in groups and on raids when you're not being hit, but your ability to keep fighting over a long period of time is important.
Unlike Frost Armor and Ice Armor, this will not snare or slow your attackers, so don't leave this up when running through a dangerous area.
This armor stacks additively with the Arcane Talent Arcane Meditation, the Fire Talent Pyromaniac and the Major Glyph Glyph of Mage Armor - in other words, if you have Mage Armor and the Glyph active, as well as 2 Talent Points between Pyromaniac and Arcane Meditation, you will regenerate mana in combat at 100% of your normal rate.
In PvP the 50% debuff time reduction can be a life-saver, especially when facing Warlocks, since a great deal of their damage comes from damage over time effects and dispellable curses.
Arcane Shielding increases by 50% the resistances granted to all schools of magic by Mage Armor, making it very useful for PvP or AoE heavy PvE fights.
Mana regen due to Mage Armor is 50%. This can stack with Arcane Meditation (+50% mana regen while casting), Pyromaniac (+50% mana regen while casting) and the Major Glyph Glyph of Mage Armor (+20% mana regen while Mage Armor is active). This results in a theoretical 170% mana regen; in reality, passive mana regeneration cannot exceed 100%.
Edit
30
Patch 3.1.0 (2009-04-14): Now grants 50% of mana regeneration while casting. Up from 30%. 
