- Get a friend/guildie to help you out
- Make sure your chance to be crit + their chance to crit < 0 so you cannot be crit
- Make sure the weapon or the sets they wear has no damaging/buffing or debuffing proc on them (e.g. no 4pc Trium/Vanq or dmg proc on weapon)
- Have them grab and activate Tortall_DPS addon (and Tortall_Core addon for it to work)
- Have them open the UI meter overlay and reset the meter from the top right
- Have them open the abilities tab on the meter UI
- Duel them
- Get them to face you directly and if they are a dw class tell them to only keep 1 weapon
- Have them attack you once so they start to hit you and then leave the rest up to their AAs
- After you die tell them to take a screenshot of the meter
It should look something like this:

- Double check that no crits happened (0% crit for both the initial ability and their AAs) or any other attacks
- For a statistically significant amount of hits (300+) the average damage divided the AA dmg will be 1 - your parry% chance
x = 1 - Avg_AA_dmg/Base_AA_dmg
In the above example we have x = 1 - 255.69/277 = --> parry = 0.077 = 7.7% here

And indeed out of 14 (hits) -1 (ability hit) = 13 (AAs) they parried 1
1/13 = 0.077 = 7.7%
- If you die too fast you can repeat the experiment a couple times and average the parry% chance:
(Parry_exp1*AA_number_exp1 + Parry_exp2*AA_number_exp2 + Parry_exp3*AA_number_exp3)/(AA_number_exp1 + AA_number_exp2 + AA_number_exp3)
e.g. Experiment 1 = 30 AAs 3.3% parry, Experiment 2 = 33 AAs 6.1% parry, Experiment 3 = 34 AAs 8.8% parry
Average_parry = (30*0.033 + 33*0.061 + 34*0.088)/(30+33+34) = (1+2+3)/(97) = 0.062 = 6.2%
- Finally, check if the average parry you calculate lines up with what you'd expect with their strikethrough and your parry%