The Avatar of Essence is a xel'naga construct that embodies evolutionary potential. In an alternate timeline where Zeratul survived the beginning of the End War, Zeratul was able to deploy these once he assembled three artifact fragments, supporting his forces with massive entropic blasts, evolving his forces to fight quicker and devolving enemies.
The Avatar of Essence can be chosen by Zeratul as opposed to the Avatar of Form when all three artifact fragments are found, and serves as his ultimate calldown. Friendly units near the construct gain buffs, and at Level 14 enemy units can be turned into lower tech units of the same race. They can float up and down cliffs, and be attacked by both ground and air units.
Friendly units around the Avatar of Essence will continuously evolve every 15 seconds, gaining attack speed and damage reduction over time. Increases attack speed by 25% and damage reduction by 10% each level, up to a maximum of 4 levels.