The Defender has a -X% chance to use Special Attacks, instead they gain a bonus based on their Current Power:
Less than 1 Bar: Reduce all incoming Damage by X%.
1 Bar: Gain +X Block Penetration.
2 Bars: All Attacks are Unblockable.
3 Bars: All Attacks are Unblockable and Charging a Heavy Attack deals X% of the Defender's Attack as Direct Physical Damage.