Tear of Isha
The Tear of Isha was a stellar manipulator. It was kept in the Omega Arsenal originally meant as a tool for stellar engineering. The Tear was designed to collapse black holes by pulling all surrounding matter into a gravitational singularity after deployment. Its appearance was described as a small rocket, implied to be bigger on the inside using Time Lord technology.
During the Last Great Time War, Rassilon ordered the use of the Tear on the Tantalus Eye, in order to prevent a Dalek plan to wipe Gallifrey from history so they would win the conflict. However, the use of the Tear would cause the Eye to implode and the ensuing storm would ravage dozens of inhabited planets near it and causing them to age to dust. This plan, and the deployment of the Tear, was prevented by the War Doctor, who travelled to the end of the universe. Cinder then fired the Tear from Partheus's TARDIS into a red giant, collapsing the star so that the Time Lord armada about to enact the plan was forced to retreat without their weapon. (PROSE: Engines of War)