Version 1:
The only thing that matters in the amount per source. You multiply the chance of being hit each time you have a source of dodge, which is:
1 - DodgeChance = ChanceToBeHit
So if you have 5% dodge from runes, 2% dodge from masteries, and 11% dodge from items:
1 * 0.95 * 0.98 * 0.89 = 82.9% chance to be hit, or 17.1% dodge
Hard cap on dodge is 80%, but you can't get it anymore because Phantom Dancer no longer gives dodge.
Version 2:
The best way to show how dodge works is an example, let's say you have 10% dodge in your runes.
10% dodge.
You grab Ninja Tabi, which gives 11% dodge.
11% dodge +
(89 * .1) = 8.9% dodge
For a total of 19.9% dodge. (Note that the 89 comes from the percent remaining from the previous dodge percentages have been calculated.)
You then get Phantom Dancer, which gives 20% dodge.
20% dodge +
(80 * .11) = 8.8% dodge +
(71.2 * .1) = 7.12% dodge
For a total of 35.92% dodge.
- I don't get the second version, so I digged around and got the first version, which I understood.