Cunning Evasion( Player's Handbook II, p. 78)
When an area attack detonates around you, you use the chaos and flash of energy to duck out of sight.
Hide 9 ranks, evasion,
Evasive Maneuvers (EE) ,
If you are caught within an area attack whose damage you avoid completely due to your evasion or improved evasion ability, you can make a combined Hide check and a 5-foot step as an immediate action. You can attempt this check only if there is cover suitable for a Hide check, and you can take your 5-foot step into cover before making your Hide attempt.
If you have the hide in plain sight class feature, you do not need cover near you to attempt the Hide check allowed by this feat.