Kog has a unique weakness to OnHit defenses that no other ADC has
Doubles the effectiveness of Amumu and Fizz' damage reduction against him.
Takes double damage from Molten Shield and DBC.
Takes double damage from Thornmail's armor component.
These effects all make counter-picking Koggy pretty easy. Shouldn't he be getting some kind of compensation for this weakness?
If Riot wouldn't mind sharing their vision and direction with Kog, I would love to hear it. So far we've had communication blackout on the Voidpuppy since the Preseason Followup thread. And even then, it was just 'we undershot his power' and not much else.
- the lifesteal and active help to keep you alive against the damage you'd take and the on hit effect helps against thornmail because that damage is unaffected by thornmail's 15% reflection passive.
- your "heal off of all my on hit damage" item. So much of Kog's damage is on hit and this item will be more effective at healing you than plain lifesteal will for Kog'Maw.
- your best defensive marksman option. The magic resist is what is most effective at reducing the damage against on hit effects like thornmail. You also get 10% lifesteal to effectively multiply your defenses.
- more of a niche option (in my opinion) because the damage doesn't scale for you as much as other attack speed items but it can be good in some situations. The magic resist you get from Wit's End will exceed that of Mercurial Scimitar and the MR shred will also help to deal some extra damage through your W.