Mage's Buffs are all very practical, Use Mirror Image all the time. Intellect is the basic attribute of Mage. Mirror Image will increase Intellect and in that case increase Mage's Crit Chance and Mana. The reason we choose Molten Armor is because it can provide 3% Crit Chance Bonus. This is very good improvement for leveling. You can also choose Mage Armor, which can regenerate 30% mana during combat. With the improvement of Glyph of Mage Marmor, the effect can be increased to 50%. When dealing with Mob of Caster, use Dampen Magic, which can reduce damage from mobs.
Mage's buffs normally can last 30 minutes, only Dampen Magic and Amplify Magic last 10 minutes.