We have a Kobold Barbarian, with Shifty from Monster Manual 1 p278.
If he activates Rage Drake’s Frenzy (Level 1 Daily, PHB2) and reduces a unit to 0 HP, he is granted a MBA as a free action. Can he use Shifty before making the MBA?
It does not matter if you use the Shifty or Shifty Maneuver (as any kobold should since 17/4/2012). Both take actions other than free, so you can not squeeze them between the trigger of an action (killing an enemy), and the action itself (making an MBA).