Only Down From Here Ultimate is a primary ability.
When you hit someone, the higher you fell from, the more damage they take.
The multiplier is calculated like this (same as normal ability):
1 + (Math.min(25, fallDistance))/20
with a max of 2.25x damage.
Make sure to use an axe, as it's not additive, it's multiplicative, unlike the mace.
Obtaining