WarframeAlchemyLab ES
Ice Storm

Farming plan

Ice Storm

Arsenal: Ice Storm
Dropped by
Sister Of Parvos (Ascension Mode Steel Path) Uncommon 20 %
Nightmare Mode Rewards, Rotation A Uncommon 18.97 %
Sister Of Parvos (Ascension Mode) Uncommon 6.6 %
Chance of getting it by number of runs
0% 25% 50% 75% 100% 3 6 9 12 15 4 runs · 50% 4 runs · 50% 11 runs · 90% 11 runs · 90%

Each run has a 20% chance. The curve is 1−(1−p)ⁿ: there is never a guarantee, only growing confidence.