I just started a monk (second char), and wanted to know how dodge stacking works. A cursory search failed me, so I reverse engineered the formula, and thought I'd share it with you all:
So it isn't possible to get 100% dodge chance by stacking dodge buffs (unless one of those buffs is 100%, which doesn't exist in game). Dodge buffs are multiplicative, but not directly as dodge, rather chances to be hit are multiplied instead. At very low dodge numbers, this is very close to adding dodge percentages, but at higher dodge numbers you will see it falling significantly short of what you'd get by adding up your dodge bonuses.
Process of reverse engineering, spoilered for cleanliness:
29.6 guardian's path (+15)
40.2 base + guardian + mantra (+15 +15)
49.1 base + guardian + mantra + mantra temp (+15 +15 +15)
49.7 base + guardian + mantra + lightning flash (+15 +15 +16)
57.3 base + guardian + mantra + mantra temp + lightning flash (+15 +15 +15 +16)
Assumption: reasonable humans came up with the formula. Rather than using regression, we guess that if they aren't adding or multiplying dodge chance, they're probably adding or multiplying something else. If I were designing it, I'd multiply chances to be hit, so lets test that.
raw dodge = .172
raw chance to be hit = 1 - raw dodge = 0.828
likewise for guardian's path 1 - .15 = 0.85
0.828*0.85 = .7038
1 - .7038 = 0.2962 rounds to 29.6% which is what we see in the raw data.
add in the mantra, another 0.85:
.7038*0.85 = 0.59823
1 - 0.59823 = 0.40177 rounds to 40.2% dodge again what we see in the data.