Obscured Avoidance
Stealth Utility 2
Although your enemy's attention is on you, its inability to see you clearly can keep you out of harm's way
Personal
Requirement: You must be marked and have concealment from the creature that marked you.
Effect: The marked condition ends on you.
Obsured Avoidance is an at-will power available to characters who are trained in stealth at second level.[PH3:175]