The Nunu Changes

Base AD increased from 67 to 70 Consume (Q) [New Effect] Well Fed now additionally grants 3/5/7/9/11 (+5% AP) magic damage on basic attacks. "(the new on-hit bonus from Q is per stack, so you can get 5x the listed amounts if you're super well fed)"

Blood Boil (W)
    [New Effect] Now additionally increases AP by 40% for both targets
        Max: 40/60/80/100/120 AP

Now, the on-hit magic damage is welcomed back with open arms. It's not quite the same as old Consume (you got 1% max health as magic damage on autos and abilities), but it's still greatly appreciated.

The AD increase is not needed and likely will be more of a headache than it's worth. He's already getting more damage on his autos with the Consume buff, he doesn't need more.

The real concern I have, though, is the Blood Boil effect.

Obviously, AP support Nunu loves this and thinks it's hilarious. Hell, even tank Nunu might try to build Rod of Ages or Liandry's Torment instead of an MR item, and it definitely makes the change to Resolve / Sorcery easier to swallow. However, giving 120 AP to yourself and your AP mid laner is a lot of invisible power (especially as Blood Boil does not have the standard 0.25 second casting time that most abilities in the game have).

This really does feel like a bad change that's going to result in some broken combinations (like Nunu/Ryze) that's going to get the Yeti Rider nerfed. When really, all he needs to be viable is some hard CC, like every single other tank in the game.

Nunu would be just as broken as Leona and Rammus if he could actually USE Aftershock. But he can't. It's disgusting how badly these rune changes have hurt him, and how little Riot prepared to stop the bleeding.