Orb of the Magi
+140 Ability Power
+10% Cooldown Speed
Gains 12 ability power and 110 HP every 30 seconds. Stacks up to 10 times.
From the Ashes
When the hero gains a level, 20% of HP and mana are restored over 3 seconds.
For a majority of mages, this comes as the first item built, the reason behind is twofold. First, it takes time to stack up and in order to reach its full potential, you need to build it early. Second is sustain from gaining a level, this alone can provide enough mana and hp so you will rarely return to the base. The exception to this rule can be champions who benefit greatly from slow like Frosty's Revenge provide.