Nunu? Is this a joke of some sort?

Nunu is actually so overpowered at the moment it's disgusting. He becomes unkillable even when playing at a deficit and still puts out good consistent damage. I just witnessed a Nunu flash into the pool to kill an adc and I thought it was glitched because he survived for so long in the pool. With spirit visage, zzrot and deadman's plate he was able to survive long enough in the POOL to finish off the adc over approximately 3-4 seconds. Did I mention that he was INSIDE OF THE POOL? It's not fun to play with him in game regardless if he is on your team or not. Incredibly unbalanced.