Two standard current meta mage builds for season 5. Works well with most mage playing mid in Conquest, and also for other game modes. Build order may vary, many other items are good for some Gods (and not so good for others) etc.
Build 1 is Book of Thoth and Book of the Dead combo. Provides a ton of Magical Power. It's a more high target damage oriented build with sustain from Warlock's Staff HP and Mana and Book of the Dead's passive of course.
Build 2 is a typical mage lifesteal build, combining Typhon's Fang with Bancroft's Talon for huge Magical Power and lifesteal. For Mages that does well with lifesteal or that deals tick of damage.