Isop-tope
From Tardis Wiki, the free Doctor Who reference
The Isop-tope, also known as the Web Destructor (PROSE: Doctor Who and the Zarbi) was a weapon created by the Menoptera to defeat the Animus when it took over Vortis. It was designed to rapidly decay cells.
Barbara Wright used the Isop-tope to attack the Animus, needing to focus on its dark side. She believed it didn't work, but the Animus became distracted by Ian Chesterton and attacked him with light. She was then able to use the Isop-tope on the dark side and decayed the Animus. (TV: The Web Planet)
