Viktor nerf harder than Kassadin's?
They're nerfing (in the PBE) the ability power Viktor gets from his Hex Core upgrades too much for him to be effective at all. On average, you can get the 1st Hex-core upgrade at around level 8 or 9. With the new hex core, you only get about an additional 16 or 18 ability power for 1000 gold. That's less than an amplifying tomb at 450 gold.
Where's the logic in this?

A reduction on the scaling ability power would be more acceptable.
is one of the most efficient items in the game with 168 AP and 500 Mana in addition to buffing all of your abilities. Before the Hexcore was lackluster and was arguably the most wasted slot in the game. The Hexcore should be powerful to make up for not having a sixth item slot where you could put, say,
or
but it's extremely efficient in it's current iteration even ignoring the spell bonuses themselves. A nerf to it is better than reducing ratios or nerfing Viktor himself.