How does the locket of iron solari work now?

Hello.

As the title suggest, how does it work guys?

It say it creates a field and damage dealt to champions is 3800% lowered (ehm, 3800%? What is it based on?). On my screen I don't see any field effect and it gives a shield as it used to do. What is different about the item now except that little glowy bird animation on ground under the caster and weird percentage?

Thanks!