If the sum total of your dodge+parry+block+miss = 102.4% AFTER diminishing returns, then any attack made against you by a level 83 (I.E. Boss Mob) will be either a block, or avoided.
This comes from the 100% needed against a level 80, plus 0.8% for each level after that (which comes from 0.2% per each stat per level).
However, don't go out of your way to get this. For one ICC pretty much makes it undesirable with chill of the throne. Don't go gemming for it.