Depleted mana rune after 55+ runs. And maybe a way to increase drop chance?

https://preview.redd.it/huglgbmloogh1.png?width=1086&format=png&auto=webp&s=acebf580a6b0e3e9a858aa29bd45c1b9540de5d8

Finally got it after 55+ runs. At my 54 run, I was thinking since the boss always talk before dying, should I let him talk more in order to take the quest? So at my last run I tried to wait and let him do more mechanics before killing, and suddenly it dropped. Maybe the boss fight time can affect the drop.

Same thing happened for my voices drop as well, I was distracted and died 3 times in that run and got voices finally. Very low sample size and could just be RNG :)