Utilizing Visionary can enable Nunu to constantly harass with Ice Blast and heal with Consume. Blood Boil can also be utilized to trigger Visionary more often, especially if laning with a friendly ranged hero like Ashe or Tristana.
Consume allows Nunu to stay in a lane against ranged opponents, especially against Heimerdinger's H-28G Evolution Turret which can be destroyed with a single Consume. It also allows Nunu to be a very effective jungler due to its healing and true damage.
You can use Consume to heal yourself if a fight is not going your way, or to heal some health if you are trying to escape from an enemy. It can often help you avoid death if you Consume an unit while retreating.
Blood Boil has a 15 second cooldown and lasts for 15 seconds. It can be cast on an ally or minion (or just yourself if jungling) and you will still receive the same effect. You should try to always have the buff active.

[Note: These items are for a game against melee characters, clearly, and the force of nature should only be bought if there are a few champions that use magic.]

[Note: This skill sequence isn't for a jungling Nunu]

Pros
- Plenty of health
- Plenty of defence
- Self Heal
Cons
- Slow movement speed
- Low attack speed and power