3 Offensive trees, 1 Utility tree and 1 Defensive tree

I have a feeling that a 6th defensive tree axed on defensive aspect could be needed. A one that focus more on Armor and Magic resist and resolve could stay focused on Health.

What makes me feel that :

• A keystone is needed for some tank jungler (Nunu, Dr. Mundo, ...) and some other case might need some other keystones too (Singed, ...)
• Health is your go to to tank things, a new tree that gives you +10 armor/mr and +12 on aspiration (130 and 145 with resolve currently) would offer new option/synergy for tank.
• You have a lot to chose for dealing damage, but not that much about tanking.

Of course, things aren't this easy, as creating 3 new Keystone is hard, but a few things that could be done about this new defensive tree would be :

• The resolve row of (+5 armor) or (+5 mr) or (+ 8 armor/mr at 10min) could be swapped into this new tree.
• (Keystone) Something about increasing armor/magic resist in the beginning of a fight
• (Keystone) Something about increasing armor/magic resist the more and more you stay in combat with champion

So what do you think ?