Heavy Warrior

Once per battle
Free action

Once per battle while wearing heavy armor, when you are hit by an attack that targets AC, as a free action, you can take half damage from that attack instead.

Adventurer Feat: 

Once per day, you can use Heavy Warrior twice in a battle (against different attacks).

Champion Feat: 

You can also use the power against an attack that targets PD.

Epic Feat: 

Once per day, you can reroll a recharge roll for a magic armor power.