Well, some numbers.
Stats: Level 46, Dexterity 391, +21 parry, +46 dodge
1. Buffs: None
18.90% melee evasion (7.74% dodge, 7.47% parry)
Diffrence: Bonus of 3.69%
2. Buffs: Aum Ti
23.28% melee evasion (7.74% dodge, 12.47% parry)
Diffrence: Bonus of 3.07%
3. Buffs: Eternal Crane Stance
32.34% melee evasion (15.74% dodge, 15.47% parry)
Diffrence: Bonus of 1.13%
4. Buffs: Crane + Aum Ti
36.34% melee evasion (15.74% dodge, 20.47% parry)
Diffrence: Bonus of 0.13%
5. Buffs: Reed the Wind
62.85% melee evasion (57.74% dodge, 7.47% parry)
Diffrence: Penalty of 2.36%
6. Buffs: Aum Ti + Reed the Wind
64.86% melee evasion (57.74% dodge, 12.47% parry)
Diffrence: Penalty of 5.35%
7. Buffs: Eternal Crane + Reed the Wind
72.49% melee evasion (65.74% dodge, 15.47% parry)
Diffrence: Penalty of 8.72%
8. Buffs: Aum Ti, Reed in the Wind, Eternal Crane.
74.11% melee evasion (65.74% dodge, 20.47% parry)
Diffrence: Penalty of 12.10%
It's all just simple mathematics. There is no bonus or penalty involved. There is no artificial soft cap.
1 - [1 * (1-avoidance1) * (1-avoidance2) * (1-avoidance3)]
Then you just have to be aware of the inherent 5.00% avoidance that we get. If for some reason another avoidance factor is involved just add another block for avoidance4.
Your Case 1.
1 - [1 * (1-0.0774) * (1-0.0747) * (1-0.05)]
Your mathematic avoidance would be 0.1890 or 18.90%
Your Case 8.
1 - [1 * (1-0.6574) * (1-0.2047) * (1-0.05)]
Your mathematic avoidance would be 0.74115 which should round to 74.12% but the game is just displayig to 74.11% rather than rounding.
If you don't understand the mathematics behind this, I'll use realworld numbers to illustrate what is happening.
We'll use your case 8 as an example. Lets assume you stood there while something attacked and hit you 100,000 times.
You would dodge 65.74% of the hits. This means 65,740 hits would be dodged. Which means 34,260 hits went through.
Of those 34,260 hits, 20.47% of them will get parried. This means 7,013 of those hits will get parried. So after being dodged and parried only 25,247 hits are going through.
Of those 27,247 hits, another 5% will be avoided with your inherent avoidance. This means 1,362 more hits will be avoided, leaving a grand total of 25,885 hits get through.
Or in other words you avoided 74,115 hits out of 100,000. A grand total of 74.115%
It doesn't matter which way you apply the various avoidance numbers it'll all come out the same.
Regards,
Croaker