In 2502 he was assigned to the isolated Protoss Advance/Experimental Facility (PAX), known for their cutting edge scientific research and their willingness to go beyond ethical boundaries. Along with fellow zealots Akam and Golarath, he was assigned to deliver a creep sample to the facility and remain on guard in the event of anything unexpected. Seeking a way to eradicate creep, PAX infected the sample with a genetically engineered virus designed to destroy it.
He and Golarath were observing a sample when the creep suddenly grew over the two of them. Golarath severed his psionic appendages and killed himself, while Ruom fell into catatonia, his mind filled with disturbing images. Underneath his thoughts, there was felt a frightful presence... Then, he was put into an isolation cell.
While in isolation, Ruom was transformed, while the mutated creep set about "fogging" the Khala, causing visions of previous unethical experiments among the protoss scientists, which drove them mad. Other protoss began to feel that there was something "wrong" within the Khala. Ruom eventually flew into combat, still using his psionic blades against the remaining protoss, killing all but one scientist, Gruu. The latter fled to the chamber holding the creep, overloading the temperature regulation mechanism and freezing the entire facility.
The abandoned facility was later discovered by a terran military expedition. They found the mutated creep to still be alive...