Predecessor Builds > Morigesh > Magic Cannon

Build the items in that order and you'll have over 700 magical power. The Orb, Azure Core, World Breaker, and Crown all add build far more into your stats than their top numbers say, and you just can't argue with the affective less of adding all that magical penetrstion from Caustica on top of it. Plus a whopping 40 Magical Haste. This is honestly a stellar build on most mages. Enjoy wrecking face.