The Purity of Form is a protoss void ray built under the oversight of the Hierarchy following the Khalai's exile to Shakuras. It was manned by both Khalai and Nerazim, and commanded by Feranon. During a battle against the zerg, the ship's void lens, the young Dark Templar Althai, was killed when he drew more power from the Void than he could handle. This caused some tension between the commander and the void lens' teacher, the Elder Theromos, who had advised against using more power. A new student, Sharas, came aboard, and proved more equal to the task. However, she too was eventually tempted by the power of the Void, and Theromos had to link his powers with hers to save the Purity of Form. He then agreed to become the ship's permanent void lens once Sharas' training was completed.