http://na.leagueoflegends.com/en/news/game-updates/patch/patch-619-notes#patch-kogmaw
Let’s start with the bottom line: Kog’Maw’s being partially reverted to his pre-2016 status. While we’ve had champions that take a couple of passes to get right (...Ryze), this is the first time we’ve actually gone back on a Champion Update. To understand how we got here, let’s take it all the way back to last year’s pre-season.
Our goal for the Marskman update was to create strategic identities for them outside of ‘who does the most damage’. What does each marksman do that their classmates don’t? Kog’Maw already had an answer to that question: be the glass cannon, demanding an entire team’s resources to support. So rather than create a distinct identity, we took a different approach: sharpen the one he already had. If ‘glass cannon’ was cool, could we push things further and make a ‘glass turret’?
10 months and 5 attacks per second later, how did that shake out? Well, Kog’s gameplay has actually moved away from the niche he previously filled. Transforming into an immobile turret is certainly unique, but it creates a ‘feast or famine’ situation. Kog can’t move between attacks in the late game, so either he mows down everyone in range, or enemies walk to safety since Kog can't keep pace. Compared to the consistent payoffs of old-school ‘Jugger-Maw’ comps, playing with today’s Kog’Maw feels too hit-or-miss.
As an aside, new Kog's created some warping effects on the items system. Specifically, on-hit items (Rageblade, Wit’s End, even Skirmisher’s Sabre) are balanced with the attack speed cap in mind, and Kog'Maw's pushing the strength of these effects past their designs. This puts heavy restrictions on the item system, all to support a single champ.
All said, we’re left with two choices - continue to make concessions toward Kog’Maw’s ‘glass turret’ ideal, or hit the reset switch to a stabler (though still imperfect) Kog. The updated kit's moved too far from what made Kog’Maw special, so we opted for the latter. This transition may be choppy, as many of League’s underlying systems have changed since Kog'Maw's update, but we’ll be monitoring how he readjusts and make any changes necessary to support him.
Total number of times scripting is mentioned or hinted at: 0