Dice Fighting-Advanced(Defending For Another)

Lets say you want to take a blow for an ally. This is a standard defence Roll made with a -2 penalty.

You make the defensive roll instead of the intended target. if you fail by 10 or more then the target is hit anyway. if you fail by 9 or less you take DMG instead of the target. If you do this you take a cumulative -2 penalty on all Attacks you attempt the next turn.

Success, obviously, means that you blocked for the person instead of putting yourself in the way to take the hit. Barring obvious circumstance (Area of Effect spells. Using the wrong defense on an unblockable attack. etc.)