Once per round as a free action, roll a normal save (11+) to intercept an enemy who is moving to engage and attack one of your nearby allies. You can pop free from one enemy to move and interpose yourself in front of the target of the attack (if you are engaged with more than one enemy, the others can take opportunity attacks against you).
The moving enemy makes its attack with you as a target instead. If you’re wearing heavy armor and a shield and the attack hits, you only take half damage.
Adventurer Feat: You can pop free from up to two enemies when using Interposition
Champion Feat: The originating enemy takes a negative to his attack roll equal to the value of the escalation die.
Epic Feat: Spend a recovery as a free action after you resolve the attack and incoming damage.