Frost Spikes

Leaves a frost patch that reduces the movement speed of enemies by 60% for 2 secs.

Bone Spikes' damage turns into Cold.

Unlocked at level 25

Crystallization

Each enemy hit has their attack speed reduced by 20% and your attack speed is increased by 3% for 3 seconds stacking up to 10 times.

Bone Spear's damage turns into Cold.

Unlocked at level 25

Devouring Aura

Becomes an aura that consumes all corpses within 15 yards to restore 11 Essence per corpse.

The range of this effect is increased by 50% of your gold pickup radius.

Unlocked at level 38

Aura of Frailty

Becomes an aura that curses all enemies within 15 yards.

The range of this effect is increased by 50% of your gold pickup radius.

Unlocked at level 39

Harvest of Anguish

Bone Armor also increases your movement speed by 1% for each enemy hit.

Bone Armor's damage is turned into Cold.

Unlocked at level 48

Metabolism

Provides an additional charge but doubles the health cost.

Unlocked at level 60