Yal Phaath was a Master Shaper of the Shaper caste. Venerable even by the standards of his long-lived race, the marks of Domain Phaath had faded by the time of the Yuuzhan Vong War due to his many escalations. He was also distinguished by the usual augmentations of his rank: two shaper hands, and yellow mqaaq'it implants.
Charged by Warmaster Tsavong Lah with eliminating the Jeedai problem, Phaath initially worked in parallel with Mezhan Kwaad on Yavin 4; it was he who sent Shaper Initiate Tsun Qel to discovering that she and her Adepts were practicing heresy. Before the heretics were rounded up, however, Yal Phaath was reassigned to Myrkr, where he began working on Shaping the vornskr into a truly deadly creature. The process was long and arduous, and resulted in many failures, partially because of the outdated nature of the Shaping protocols, partially because of Phaath's determination to avoid any whisper of heresy in his work; but eventually, the Shapers succeeded in creating the voxyn in their damutek aboard the Baanu Rass.
After Supreme Overlord Shimrra executed Ch'Gang Hool for being unable to control the World Brain on Yuuzhan'tar, Phaath was placed in charge of the shaping of the galactic capital. By the end of the war, Qelah Kwaad was the senior shaper on the planet, due to her success in creating the Slayers.
- The Complete Star Wars Encyclopedia