The title of this article is conjectural. The subject has no canonical name.
An anti-protoss weapon was developed by the Umojan Protectorate created by Dr. Robertson, in a secret lab on Spearpoint Base. It was a red, double barreled rifle, that fired a large explosive payload, especially designed to kill protoss targets. Development was largely done based on theory and calculation, and testing had not been done on real protoss.
The weapon was coveted by a Nerazim criminal, who sought to use it on her own people. She used a terran thrall Caleb to locate the lab, and stole the weapon for herself. However, as they escaped Caleb turned on her, and the weapon was destroyed when their ship careened into a Tal'darim mothership.