You can go anywhere you like, except for jungle. Honestly it doesn't get better than this. A ****load of AP and magic penetration, along with your defensive masteries to make you just a little less squishy. Dominate the enemy team with this AP Mordekaiser build!

P.S. With your flat AP runes you'll dominate early game, allowing yourself to get fed, thus there is no need for AP-per-level runes.