Funny that nunu is coming back. I was in a normal draft and watched allistar and soraka get banned and Taric picked by the opponents and I was stuck with support. Since I don't own janna I was looking through my list of champions trying to find something to support with and saw I owned nunu lol. Was going to give him a go but someone dodged. I'm going to have to give him a stab in the jungle. Still trying to find a goto jungler besides Nocturne. It's my weakest role by far.
Nunu's a pretty situational pick. I would pick him only if two other things are true: 1. You have a STRONG top, mid and bottom. 2. The enemy jungler is a relatively risky or slow jungler.
For No. 1, late game, Nunu won't be contributing much to team fights outside auras and a MS/AS buffs/debuffs to your carry and the enemy carry - you're stuck essentially with two supports. That's why you need to ensure all of your other lanes are really strong, so the lack of damage won't hinder your late game.
For No. 2, Nunu is a counter jungler. If he's facing off against someone that clears super quickly (Udyr), then he has a smaller window for counter jungling. If you're up against a high sustain jungler (Warwick) then you can steal neutrals but you won't be able to kill them. If you can't kill them, then you will fall behind because they are likely better late game.
I think the best matchups for Nunu are junglers like Xin, Olaf, Malphite, J4, Eve - people that don't clear quickly and also get relatively low during their first clear. Consume enemy wraith, ward their their red, take your blue and red for a quickly level 3 and double buff. Then make your way to their red, when you see them going for it, wait until red whittles down their health and then kill them.
I guess the reason I wrote all this: Nunu isn't an instalock jungler, he needs a good matchup to shine. If you want to learn more junglers, I would go with a more well-rounded pick. Nocturne is a good start, but people like Skarner, Shyvanna and Udyr would probably be better secondary choices.
