"The Overmind was a millennia-old brain-like entity. It was created by the xel'naga on Zerus to bring order to the zerg and guide them into merging with the protoss. At first it was only a semi-sentient entity created from the instincts and collective sentience of the zerg, but it quickly developed intellect and personality. The Overmind was created with intelligence and the ability to reason, but its free will was undermined by an overriding directive to destroy the protoss. This was part of a greater plan by Amon to remould creation in his own image. The Overmind learned of Amon's plan through scattered and confused images, which the Overmind ultimately formed into a more coherent narrative. The Overmind disagreed with its directive because it knew the zerg would be destroyed once the protoss were, but could do little to resist.

The Overmind was not an automaton, and had broad latitudes in its thinking. However, 'iron-clad' compulsions prevented it from considering rebellion. The Overmind used 'cracks' in these controls to support the goals of the zerg over Amon's."

The "fantasy" of The Overmind:

- Hive-minded: Expand your area of influence via Cerebrates, mimicking the spread of the Zerg among planets

- Endless Tide: Command an army of Zerglings on a global scale; their power resting in their sheer numbers

- A War On Many Fronts: Constant, unrelenting pressure on every lane

- Changing, Evolving: A swarm that can adapt to meet any challenge

The Overmind replaces your team's core. To enter the battle, The Overmind can spawn Cerebrates anywhere on the map that it has vision. Once a Cerebrate has been spawned, The Overmind can cast abilities and control certain units within range of a Cerebrate. The Overmind receives experience from enemies that die near a Cerebrate or an Infestor.