전설드랍율
난이도          (필드)     (일균)
보통                       1.000     1.250
어려움               1.000       1.250
고수                        1.000       1.250
달인                 1.000       1.250
고행1               1.150       1.438
고행2                1.323       1.653
고행3                1.521       1.901
고행4                1.749       2.186
고행5                2.011       2.514
고행6                2.313       2.891
고행7                2.660       3.325
고행8                3.059       3.824
고행9                3.518       4.397
고행10                4.045       5.057

[소수점 이하 반올림 했어요]

계산후 결론은,
1. 고행난이도부터 난이도1 증가당 전설드랍율 15%증가
2. 일균은 동일난이도 일반필드보다 전설드랍율 25%증가
3. 고행6은 전설드랍율 231%/289%(일균) 증가
4. 고행10은 전설드랍율 405% / 506%(일균) 증가
5. 고행10은 고행6 보다 전설드랍율 74.9% 증가

참조:http://www.realsg.com/2014/04/guide-diablo-3-legendary-farming-how-to.html?m=1