How is ap kogmaw

He is godly in ARAM.

If his W still scales with AP, I believe he is still decent.

He is good, but you need several items and he is even more vulnerable (except for Zhonias) that his AD version. He was an horrible earlygame and cant fight against assassins at all.

But with the correct team comp, he is awesome.

he was super good before they nerfed his ult dmg.

here

He is good, on the condition you can survive till level 11 (rank 2 ult) and farm well enough to have + at the very least by that point. It is less AP Kog and more magic pen kog.