Kog doesn't actually function that well as a spell-weaver
's what Riot was trying to push him as after the rework. A spellweaver like Ez or Corki, but with a stronger late game.
Disregarding the fact that 'spellweaver' isn't a champ niche so much as it is 'dude who buys Trinity', Kog really isn't that great of a spell-weaver to begin with. Allow me to explain why by way of contrast.
Ezreal is a great spellweaver because his Q allows him to make full use of Sheen from long range. Cool.
Corki is a great spellweaver because he invests in very little attack speed, allowing him to lob spells between basic attacks without losing any DPS.
Kog on the other hand, due to the existence of Rageblade and the fact that his W only scales meaningfully with attack speed, wants to hit 2.5% IAS (which he can do with Rageblade, Runes, and two other IAS items of his choice) and lay down some pain. Now, while he's laying down said pain pausing for half a second to lob an Ult is going to be reducing his DPS in many situations.
So this got me to thinking.
What if Kog's Ult didn't interrupt his basic attacks? As in, Kog can continue spewing out acid even while lobbing artillery shells into the sky. Then he would actually be able to take full advantage of both forms of DPS his kit offers without them stepping on each others toes.