p1 chaos , got jah and ber drop before my lock reach level 90
but all is just rng tbh..
Not fully RNG.
Ghosts have better rune drop odds than any other mob in the game,
And there actually is a real hierarchy with the mobs' runes drop rates.
So if you mostly farm areas that have shitty mobs for rune drops, you most likely will find less runes for the same kill count, than someone who farms areas with ghosts.
Arcane is known for its good rune drops specifically because of the ghosts.
CS has both ghosts and high density (another factor into rune farming ofc).
I am not saying only areas with ghosts drop runes at all, but it contributes to good results for sure, and rune drop is not as RNG as we may picture it, even on the roll itself to choose whether or not to pop a rune.