Basically it needs to monitor an array of damage reduction buffs like when they are applied and when they fade.
  During the time that buff/buffs are up it calculates the damage that has been reduced.
  e.g. Tank takes a hit for 50,000 damage while barkskin (20%) is active, damage reduction should show Barkskin: 12,500 damage ((50,000 / 80) * 20)
- When multiple buffs are active it would just need to place the damage reduction into each of the spells that were active in the same ratio a the percentage of damage reduction. So it needs to monitor all damage reduction buffs (Spell, Physical, and Both) and work out the amounts based on the hit taken.
+ When multiple buffs are active it would just need to place the damage reduction into each of the spells that were active in the same ratio as the percentage of damage reduction. So it needs to monitor all damage reduction buffs (Spell, Physical, and Both) and work out the amounts based on the hit taken.
  If this is too resource intensive then just making it available to the single user would be great, rather then monitoring the whole raid.

  There was an addon created previously http://www.curse.com/addons/wow/recountdamagereduction#c6
  That did exactly this. I have tried to manually update this myself and although I have gotten it to work again, there are some spells that I just can't get it to detect.

- Basically it needs to monitor an array of damage reduction buffs like the when it is applied and when it is fades.
+ Basically it needs to monitor an array of damage reduction buffs like when they are applied and when they fade.
  During the time that buff/buffs are up it calculates the damage that has been reduced.
  e.g. Tank takes a hit for 50,000 damage while barkskin (20%) is active, damage reduction should show Barkskin: 12,500 damage ((50,000 / 80) * 20)
  When multiple buffs are active it would just need to place the damage reduction into each of the spells that were active in the same ratio a the percentage of damage reduction. So it needs to monitor all damage reduction buffs (Spell, Physical, and Both) and work out the amounts based on the hit taken.