I really really enjoy playing Maoki as an AP caster! He has great burst and people will always underestimate the damage you can pump out.. I have no problems taking plenty of damage with the passive and ult in good position.
Catalyst > Rod of Ages (minute 16 is what I aim for)
Sorc boots (mercs optional obviously)
Void Staff (I think this item was made for maoki.. seriously it's that good!)
blahblah addition defense/attack..
I level R>E>W>Q
I would never try this in a ranked match..but it's so **** fun to play in normals. If my team lets me mid it's fun raping a malz or annie.