his Q skill, while a really short cooldown doesnt seem to pack quite the punch it should imo. im not able to play at the moment so cannot better test, but the AP ratio for it is less than one, probably like 0.8:1 or something like that. with the low base damage (250-280?) at max rank, you really need to get a lot of AP for it to be as powerful as other casters basic nukes (annie's fireball, ryze's overload).
The side bonus of gaining AP per minion/champion kill is great on paper, but weak in reality unless the game can go for a long time, and you are either given a lot of farm time, or are lucky with champion kills. Ive found that in a regular game if i dont buy a little mana regeneration, i cannot farm much more than 20-30 or so AP, and if i buy some regeneration early (chalice in 2-3 minutes) i can get maybe 40-50. This is in a regular game that past 10-15 minutes im not really farming in lanes much. And from that experience, the money spent on buying the regeneration would be better spent on just buying AP.
So, as its not a very effective method of gaining AP, i actually feel it would be better to skip this ability
until you have to take it, as you can farm a lot better, and do better in team fights with maxed out cage/dark matter. As it really looks like the intended playstyle of him is to try and farm AP with his Q, it should probably be buffed. Better AP scaling on it, and slightly better AP gain off kills from it would be a decent start.