Gengi Tung was a member of the shaper caste of the Yuuzhan Vong. After Supreme Overlord Shimrra began executing several ranking shapers over their inability to control the World Brain of Yuuzhan'tar, Tung found himself escalated to Master Shaper.
The escalation came as a surprise to many other shapers—none more surprised than Tung himself. However, he refused to let anyone humiliate him, or be brought down by some ambitious Domain. As a result, Master Tung often accompanied warriors into the field, searching for renegade Coruscanti, wielding a Tsaisi instead of the whip sting so commonly found in shaper hands. At all times, he was accompanied by Toi and Tixo, his two pet umrachs.