So the Ranger has to declare his use of Roll With It before he learns the area of an attack? That seems crazy to me. (And if he gets to know the area, it seems asymmetrical punishment for the Wizard.)
Are you talking about Hit the Dirt?
Comparing the utility of a 22nd level Utility power with a 2nd level Utility power?
Don't you think that a 22nd level Utility SHOULD have a lot more utility than a 2nd level Utility power?
And of course, where exactly does it state that the Ranger knows the area of an area effect power used against him?