hmm since when does veil block a spell every 30 sec
and Kog'Maw's squeamishness isn't a problem because they shouldn't be able to reach you to begin with moreover his health exceeds that of most mages and carries in the game
im not saying that he is not squishy though and veil's passive will block something like living artillery 95% of the time

Thanks for the feedback :)
I love the mana regen per level cause you dont have to go to base so often and you can spam your W to harass and use your ultimate to scout without losing much mana.

More comments and ratings please!

You will have some benefit from armor pen but the benefit from magic pen far outweighs it. Replacing SotD with frozen mallet is a good idea. :)

I'm not sure if you're asking about armor or armor pen. Armor seals are ok, but kog should be staying in the back and not getting hit by the enemy ad heroes (hopefully). I like the mr glyphs because they'll help you early game where casters tend to be more strong. For the seals I would just keep them how they are with the mana regen.

I agree with the with the frozen mallet and i would replace it with the SotD cause Wit' End is more useful, cause of the magic resist.(my opinion)

And the magic pen marks and quints I agree with you. Glyphs again, I agree with you. But would armor be any good?

Turn your marks and quints into magic pen, you are still dealing mostly magic damage (madred's is magic damage, W is magic damage, sword of the divine is magic damage) and they will make you deal a lot more damage. For the glyphs I'd change them to magic resist to make you a lil less squishy.

For masteries take Awareness over Expanded Mind. I can show you the math if you don't trust me but since Expanded Mind only works off base mana it's pretty terrible, extra exp is much better.

I'm concerned you might have trouble killing people without frozen mallet to slow them. The health is nice too, have you tried it? I personally would replace SotD or Wits with Frozen Mallet.