Heirlooms don't stack (chest + shoulders) don't give additional 20% experience, but rather give 10%. This is significant because it could possibly mean that stacking with helmet (which would total to 30%) would not work either, which combined with prequesting would make a huge advantage.
1.2. How to Reproduce
1. Equip both shoulder and chest heirlooms.
2. Finish a quest of your choice
3. voilá
Experienced gained is 6050 (increased from 5500) which means it was increased by 10% not 20%. Unless I am misunderstanding how increased experience gained is working it should rather be equal to 6600, and not 6050.
5500 0.2 + 5500 = 6600
5500 0.1 + 5500 = 6050
1.3 Source Material
Athene's world first lvl 85 video
Not really necessary to look for source, since it's looks like a math error but, blue posts indicates that they would work on lvl 80 (thus helping 80-81). Good source is from Athene world first lvl 85 video where he leveraged similar trick.
2. Expected Behavior
2.1. Description
Given 20% bonus gained experience (or 30% with helmet, though I don't have access to it yet so couldn't test it).
1. Current Behavior
1.1. Description
Heirlooms don't stack (chest + shoulders) don't give additional 20% experience, but rather give 10%. This is significant because it could possibly mean that stacking with helmet (which would total to 30%) would not work either, which combined with prequesting would make a huge advantage.
1.2. How to Reproduce
Experienced gained is 6050 (increased from 5500) which means it was increased by 10% not 20%. Unless I am misunderstanding how increased experience gained is working it should rather be equal to 6600, and not 6050.
5500 0.2 + 5500 = 6600 5500 0.1 + 5500 = 6050
1.3 Source Material
Athene's world first lvl 85 video Not really necessary to look for source, since it's looks like a math error but, blue posts indicates that they would work on lvl 80 (thus helping 80-81). Good source is from Athene world first lvl 85 video where he leveraged similar trick.
2. Expected Behavior
2.1. Description
Given 20% bonus gained experience (or 30% with helmet, though I don't have access to it yet so couldn't test it).
2.2 Source Material
See 1.3.