DDR does not pass 100%, its capped at 95% (mids is lieing to you AHHHHHHH!) at which points you should be getting 5% of the strength of a def debuffs.
So i think something like this should work: debuff*1-DDR%
...At least i think.
"I have ridden the mighty moon worm!"
-Al Gore
Fiery Aura is only good for farming, I'm cereal
@Caucasiafro
Resistance of any sort (except mez resist) is calculated as Effect*Resistance.
So if you take 100 Smashing damage and have 18% Smashing Resist, you take 82 damage.
Likewise, if you take a 40% Defense Debuff and have 95% DDR, you are affected by 5% of the debuff, or a 2% reduction in defense. (As ultrawatt posted)
Note that some powers, especially patches like Quicksand are autohit and unresistable, so until you get out of the area, you'll be affected by the full strength debuff.
Mez resist is applied using the Debuff/(1+resist), meaning that at 100% resistance, you are affected for half the duration, at 200% you get 1/3 the duration, and so on, and you can never push the effect to 0.
@Roderick
What is the DDR formula?
How does it work?
What happens when DDR exceeds 100%?