A validium staff was built by the Time Lords as the ultimate defence for Gallifrey. It had the ability to find weaknesses in the fabric and structure and rationalize them. However, when the Time Lords left Lethe, the staff was left behind.

As official god-killer of the Autarchy, the priest Brunner used the staff to attack, kill, and erase from time all gods that were opposed to Om. While Brunner was travelling on the Lung of Heaven, the staff noticed the TARDIS nearby, so it reached out and pulled it down into the sea; when the Fifth Doctor picked it up, it flared silver-white and began to writhe in his hand.

The time-sensitive Constantine used the staff to create the Parliament of Rats and its White God to attack the Lung of Heaven, since that's what Brunner and Korzen wanted. When Brunner tried to use the staff to destroy the White God on the Parliament of Rats, it only amplified the apparition. The Doctor spoke to the staff, which called him "my lord", and told it to dissolve; as it did so, the White God split open and the Parliament broke apart. (PROSE: The Parliament of Rats)

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