Nehra

 was the magician for a maharaja.

Nehra was threatened when another magician, the Second Doctor, showed up with his blue box and was welcomed by the maharaja. Nehra tried to find out what he could about the magician, and he used spells to examine the blue box. He was shocked to see the Earth surrounded by threads. He thought the magician was trying to destroy the Earth with these threads, and he decided to call up an "asura", or demon. However, the demon he called up, Vishathra, wasn't very bright.

After Nehra explained to the demon what he should do, the magician, who called himself "the Doctor", entered and tricked the demon into cutting its own thread. He then explained to Nehra that the threads were part of the Web of Time. Snipping even one or two threads would unravel all of causality.

Nehra wanted to make amends, so the Third Doctor placed him in charge of the airship that took certain people to the time vortex. (PROSE: The Steward's Story)