The Vaa-tumor was an enhancement specific to Yuuzhan Vong Master Shapers, and was believed to have been a piece of brain matter of the goddess Yun-Ne'Shel. The tumor was implanted into the brain of the aspiring Master, who had to endure a period of personal sacrifice as part of the process. The tumor was structured to alter the Shaper's brain structures, and enhance the mnemonic ability of the host. After developing the needed capacity, the tumor enabled the shaper to rapidly integrate the data of a qahsa into memory. Thus educated, the Shaper would later have the vaa-tumor ritually excised.
- The New Jedi Order: Edge of Victory I: Conquest (First appearance)
- The New Jedi Order: Edge of Victory II: Rebirth
- The New Jedi Order: The Unifying Force (Mentioned only)